Molecular Genetics Practical Write Up Lab Report

Molecular Genetics Practical Write Up - Lab Report Example typhimurium, and TA 1535, TA 1537, TA 1538 mutants. 2mL of molten overlay agar (kept in a 45 °C water-bath) was added in to a sterile tube. After waiting for the agar to cool slightly (roughly 37 °C), 0.1mL of the bacterial culture was added using a Gilson pipette fitted with a sterile tip. Immediately the molten agar was poured along with the bacterial strain onto a E-medium plate ensuring even distribution of the overlay agar on the plate surface. The plate was then allowed to cool before incubating at 37 °C overnight. 2mL of molten overlay agar was added in to a sterile tube and after slightly cooling, 0.2mL 0.5mM histidine + 0.5mM biotin solution was added. 0.1 mL of the bacterial culture was added using a Gilson pipette fitted with a sterile tip and immediately the molten agar was poured along with the bacterial strain onto a E-medium plate ensuring even distribution of the overlay agar on the plate surface. The plate was then left to cool and later incubated at 37 °C overnight. 2mL of molten overlay agar was added into a sterile tube. After the agar had slightly cooled, 0.2mL 0.5mM histidine + 0.5mM biotin solution and 0.1mL of the 0.1M histidine solution was added. Immediately pour the molten agar was poured onto a E-medium plate ensuring even distribution of the overlay agar on the plate surface and the plate allowed to cool. Six serial dilutions of the bacterial culture in  ¼ strength Ringer’s solution ( 10-1, 10-2, 10-3, 10-4, 10-5 and 10-6) were prepared by adding, for instance for the 10-1, 100ÃŽ ¼l of the bacterial culture in a sterile eppendorf tube and adding 900ÃŽ ¼l of  ¼ strength Ringer’s solution. This diluted culture was used to carry out the next dilution and repeat this was repeated six times in total in order to get the 10-6 dilution. The plate was divided into two halves using a marker pen and marking the bottom of the plate one side was marked 10-5 and the other side 10-6. 10ÃŽ ¼l of the 10-5 dilution was dropped using a Gilson

Classroom - Toelf Essay Essay Example for Free

Classroom Toelf Essay Essay In general, most people tend to view things differently, even whether if classrooms environment should be interactive or not. To some people, they may think that classrooms are places where teachers lecture and the students listen. However, in my opinion, I believe that classrooms should be interactive. The following cases and examples will help support my point of view. People have different backgrounds. Students, especially in international schools, have varying backgrounds, which may result in different views. A classroom is a place for learning experiences, therefore, it is crucial that varying opinions are brought to the table. Take the example of a business class. In discussing whether or not coffee stands should be locate within the campus or outside, the teacher may Do you think that students will always understand every single thing the teacher lecture about if they weren’t allow to ask questions? In complicated classes such as math or science there are many things that usually confuse the students. It is nigh impossible for the teacher to be able to make sure that everyone understands, let alone knowing whom doesn’t what. Courage. When your kids grow up, they do not work alone. Courage is an important aspect in working with others, whether it is to lead or just to follow. In the case of Pearson Hardman, an international law firm, they seek not only people with knowledge but also people who have individuality, people who could think for themselves and are not afraid to express their opinion. Where is a better place to develop those traits than in classrooms. Classrooms where students are allowed, and encouraged, to speak out their mind. In conclusion, it is hard to make all people view things in the same way, even in the case of whether or not classrooms should be interactive. Some people may agree that it should not be because discussions may lead to the teacher not being able to teaches everything he intended to. However, to me, I strongly agree that classrooms should be interactive. The examples and cases mentioned above have supported my point of view to the best.

Coca Colas Entry Strategies Into The African Market Marketing Essay

Coca Colas Entry Strategies Into The African Market Marketing Essay Coca colas entry strategies into the African market. The Coca-Cola Company is one of the largest manufacturers, distributors and marketers of nonalcoholic beverage concentrates and syrups in the world. Coca-Colas headquarters are in Atlanta, Georgia, in America. It is best known for its flagship product, Coca-Cola, and is one of the largest corporations in the United States. Today, Coca-Cola is an internationally recognized soft drinks company with ambitious plans to further grow the brand. The company owns the majority of the soft drinks available in coolers and in vending machines in the western world. Some of these brands include, Coca-Cola and sub brands1, Dr Pepper, Fanta, Sprite, Oasis and PowerAde. A full list of Coca-Colas affiliated brands can be found on their corporate website2. The 2005 Annual Report states the company sells beverage products in more than 312 countries or territories.3 The international presence of Coca-Cola is phenomenal and its logo, advertising and colours are among the most recognized in the world. When an organization has made a decision to enter an overseas market, there are a variety of options open to it. An organization wishing to go international faces three major issues: i) Marketing which countries, which segments, how to manage and implement marketing effort, how to enter with intermediaries or directly, with what information? ii) Sourcing whether to obtain products, make or buy? iii) Investment and control joint venture, global partner, acquisition? Decisions in the marketing area focus on the value chain . The strategy or entry alternatives must ensure that the necessary value chain activities are performed and integrated. . One of the critical questions to examine in establishing an international development strategy is to select the entry mode in the target foreign country and the distribution channel. Several alternative entry strategies can be considered, Multinational enterprises (MNEs) are expanding their global reach, carrying their products and brands to new and diverse markets in emerging economies. As they tailor their strategies to the local context, they have to create product and brand portfolios that match their competences with local needs. A multi-tier strategy with local and/or global brands may provide MNEs with the widest reach into the market and the potential for market leadership. However, it has to be supported with an appropriate combination of global and local resources. Foreign entrants thus have to develop operational capabilities for the specific context, which requires complementary resources that are typically controlled by local firms.One of such an organization is coca cola company. Coke has recently started to heavily invest in the African market. Africa was actually a low priority region for Coca-Cola until 1997 when citing rapid population growth and disproportionately low sales, the company developed a new market strategy aiming to double sales in 5 years. Indeed, per capita consumption in Africa has grown from 18 servings in 1986 to 37 servings in 2006. Unit case volume sales are up 4 percent from 2005 to 2006. This growth was predominantly driven by 23 percent unit case volume growth in Egypt, after Coca-Cola opened a new divisional office in Cairo. Coke has clearly decided to focus its energies on emerging markets throughout the world and Coke can honestly brag about increasing its sales volume on a global scale. However, as new countries are aggressively targeted by Cokes marketing machine, dietary patterns change, and the rate of western-style diet-related diseases increase. Entry strategies into the African market. Coca Cola Company entered into the global market using various modes of entry. The most common modes are exporting, licensing and franchising. Besides exporting beverages and its special syrups, Coca cola also exporting its merchandises to foreign distributors and companies. The company has also started licensing with bottlers around the world and supplying its special syrup necessary to produce the product. Coca cola works with more than 300 bottlers internationally to produce, deliver, market and sell products around the world. In 1984 a candy store owner Joseph A Biedenham began bottling coca cola to sell using common glass called Hutchinson. Benjamin F. Thomas and Joseph B. Whitehead have made first bottling agreement with Coca cola. During 1900-1909, three main bottlers divided the country into territories and sold bottling rights to local entrepreneurs. In 1916, a distinctive bottle called contour bottle has been designed to distinguish from imitator. The contour bottle became trademark status by U.S patent office. During 1920s more than 1000 coca cola bottlers were operating in U.S. Between 1920s and 1930s, company leader Robert W. Woodruff began expand internationally through establishing bottling operation outside U.S. In 1940, before World War II, 64 bottling plant were setup around the world. During 1970s and 1980s many small and medium-sized bottlers consolidated to better serve huge amount of global customers. Strong licensing relationship with bottlers became the base for Coca Colas entire business growth. Franchising is a special type of licensing strategy. There is various type of franchising. The type used by Coca Cola is manufactured-sponsored wholesalers franchise system. In franchising the finished products and sold to the retailers in local market. In case of Coca Cola Company licensing proved most suitable mode of market entry. T he licensing strategy must ensure ongoing competitive advantages such as export market opportunities, low-risk manufacturing relationships, and diffusion of new products. Other market entry mode such as exporting also proved useful in expanding globally. à ¢Ã¢â€š ¬Ã‚ ¢ Coca-Cola has massive world appeal. The products image is loaded with over-romanticizing, and this is an image many people have taken deeply to heart. The Coca-Cola image is displayed on T-shirts, hats, and collectible memorabilia. This extremely recognizable branding is one of Coca-Colas greatest strengths.7 à ¢Ã¢â€š ¬Ã‚ ¢ Additionally, Coca-Colas bottling system is one of their greatest strengths. It allows them to conduct business on a global scale while at the same time maintaining a local approach. The bottling companies are locally owned and operated by independent business people who are authorised to sell products of the Coca-Cola Company. Because Coke does not have outright ownership of its bottling network, its main source of revenue is the sale of concentrate to its bottlers. Other brands owned by the Coca Cola company that have a strong brand image.8 à ¢Ã¢â€š ¬Ã‚ ¢ Seasonal advertising awareness e.g. TV Christmas advert and summer advert. à ¢Ã¢â€š ¬Ã‚ ¢ Coca-Colas brand name is known well throughout 94% of the world today à ¢Ã¢â€š ¬Ã‚ ¢ Coca-Colas bottling system also allows the company to take advantage of infinite growth opportunities around the world. This strategy gives Coke the opportunity to service a large geographic, diverse area. . Coca-Cola has successfully employed the hub-and-spoke model in multiple rural emerging markets. In Africa, for instance, 9 Coca-Cola set up Manual Distribution Centers in which an independent person was given the rights to distribute Coca-Cola products within a defined radius14. Similarly, in India local entrepreneurs sell Coca-Cola using all possible means of transport, ranging from trucks, auto-rickshaws, cycle rickshaws and hand carts, to even camel carts in Rajasthan and mules in hilly areas, to transport its product from the nearest hub.15 (See exhibit 3) As Colgate and Coca-Cola have shown, the hub-and-spoke model for FMCG products works well because it addresses the inventory cost and transportation infrastructure issues that are associated with distributing products in rural emerging markets while also providing for good product availability at the small-village level. In the villages, farmers earn the bulk of their income during two to three peak harvest months, earning nothing during troughs. Farm labors get a daily wage when thereà ¢Ã¢â€š ¬Ã… ¸s work to do; at other times they sit around idle, migrate to towns, or scratch a living from other sources.36 Equally important is the ability to execute on the ground and deliver consistently across this wide variety of markets, even as they change and mature over the longer term. Many of the early entrants to Africa have established successful, profitable businesses. Companies have been able to generate competitive advantage by influencing consumer preferences, building brand loyalty and shaping industry structure before competitors have a chance to become established. The majority of emerging market nations continue to have largely rural, agrarian-based economies.1 In Africa alone, of the seven hundred million residents , roughly five hundred million people lived in rural areas.2 Delivering products and services into this market presents both unique challenges and enormous opportunities for companies. The nature of rural emerging markets makes building a successful marketing channel challenging. The population is widely dispersed, transportation infrastructure is poor or non-existent, household incomes are low and sporadic, and traditional methods of creating brand trust and awareness will not work. I propose that an entering company needs to design marketing channels that both successfully deliver products to customers in a capital-efficient way, and that unlock the latent desire that customers have to purchase and receive those products. In this manner, not only are transporters and warehouses part of a successful marketing channel, but so are entities that educate customers about products and services they may not know they need, as are the financial programs that help customers finance their purchases. The key points coca cola company should focus on when designing their rural distribution networks in emerging markets are as follows: 1. The company should choose the distribution network model that is appropriate for the product or service it is selling. 2. While continuing to meet the customers needs, the company should aggregate consumer demand into central locations as much as possible in order to decrease inventory and transportation costs. 3. The company should consider taking advantage of rural entrepreneurs (REà ¢Ã¢â€š ¬Ã… ¸s) to facilitate last-mile product delivery and sales. Such rural entrepreneurs include retailers and kiosk operators. Although consumers in rural emerging markets clearly have low and sporadic incomes, it would be a mistake to assume that these consumers necessarily desire to purchase cheap products. Instead, as Prahalad writes, the consumers are very brand-conscious and are motivated to buy quality goods. However, at the same time, they are by necessity very value-conscious.37 The challenge for companies entering this market is to offer consumers high-quality products and brands while also offering . When AIDS advocates in Africa noticed that Coca-Cola products were available in remote African villages, it sparked the idea that perhaps the companys supply chain experts could assist in delivering life-saving drugs to AIDS victims. The drugs are typically hard to come by, especially in the outlying regions of poor countries. In some regions, it is not uncommon for the drugs to take 30 days to get through a nonprofits supply chain before arriving at their final destination. In 2009, the Global Fund to Fight AIDS, Tuberculosis and Malaria asked Coke for assistance improving the organizations supply chain. The company agreed to help with a project in 2010, and the corporation worked with the Global Fund, Tanzanias Medical Stores Department, the Gates Foundation and Accenture Development Partnerships to get life-saving drugs to far-flung villages in Africa. What we noticed was that Coca-Colas products always seemed to get to every remote region, and we thought that if they could get their products there, with their support, maybe we could, too, said Gabriel Jaramillo, the Global Funds general manager, according to the Daily Beast. The drug supply chain hasnt been perfected, according to a study from the Yale School of Public Health. However, it has greatly improved access to medication in rural regions. Ill patients now have an 80 percent chance of receiving the correct medication, up dramatically from only a 50 percent chance two years ago. While the old delivery systems took a month to get drugs to the correct area, supply chains have been optimized and delivery time is now estimated at merely five days. Coca-Cola isnt doing all the work for the project they give expert advice and input, but Tanzanias Medical Stores Department is chipping in and having its employees learn the basics of supply chain management, logistics and distribution. However, the project doesnt only involve learning about how supply chains operate. All the partners are working to develop infrastructure in poorer developing areas, so Coke products and medications can more easily get where theyre needed most. Due to the success of this program, it has expanded to Ghana and Mozambique, where supply chains are still too underdeveloped to get rural residents the drugs they need. By working with one of the worlds largest distributors, groups looking to expand access to AIDS medication have developed a new system to better serve ill patients in remote regions.

Revisiting Childhood in The Lion, The Witch and the Wardrobe :: Lion Witch and the Wardrobe Essays

Revisiting Childhood in The Lion, The Witch and the Wardrobe    When I was young, it was hard to understand the bigger picture. I knew not what I did; I only acted. Aggressive action came spontaneously, and in rapid response to whatever situation befell me. I frequently fought and argued with my brothers. While we were good around other people, at home, my brothers and I were not pleasant to deal with. At the time, it was impossible for me to foretell the ramifications of my mother. It was not until much later before I realized the gift that my mom had managed to give my brothers and me in her remarkable grace under the pressures. She was taking on four pre-teenaged boys on a hectic schedule, while juggling a part-time job and continuing college level education.      Ã‚  Ã‚  Ã‚  Ã‚   I was no more than ten years old when my mother began reading to us. It was a difficult enough undertaking, shuffling us between our father's house and hers and the many extracurricular activities involved with bringing up four young men. Somehow, three or four days a week, she enticed us all to sit down before bedtime for the retelling of a classic story. We started out with the first book in the Chronicles of Narnia series by author C. S. Lewis, titled The Lion, The Witch, and the Wardrobe.      Ã‚  Ã‚  Ã‚  Ã‚   In this fairy tale, a magical lion returns to the mysterious land of Narnia in a quest to put an end to the evil reign of the wicked White Witch. The story simply captivated my younger brothers and me. The strange part was that it was never about the animals that talked, the fauns, unicorns, giants, dwarfs, wolves, centaurs, beavers, and birds. Truthfully, I did not remember much about a witch in the story, much less the existence of a lion. I did not recall any morals, messages, or even a plotline. What struck me most was part of the tale that engulfed the four siblings in the adventure of their lifetime. A few times a week, my brothers and I followed Peter, Susan, Edmund, and Lucy into the enchanted wardrobe and through to the other side. As we circled around my mother in our living room, we were careful, just as Peter was, in closing the door.

A typical Victorian family Essay

â€Å"We don’t live alone. We are all members of one body. We are responsible for each other. † What is Priestley’s main aim in ‘An Inspector Calls? ‘ How successful was he? It year was 1945 when J. B Priestley created his masterpiece, An Inspector Calls. He set the play in 1912 like a typical Victorian family, the male of the family ruling the rest. He intended the play to be viewed by all but I don’t think he expected it to still be played today. The play has a very important message inside. I think the message is that we have to be careful in what we say to others because without us knowing, we could have a negative impact on whoever it is directed to. The play is designed like a detective style. It has the Inspector interrogating the suspects to try and piece together the clues into the suicide of Eva Smith. As well as the play being educational, Priestley made it entertaining so more people would watch the play closely than if it was just educational. Also more people, I think, would go and read it. Every one of us has an individual role into the way we live. We could choose to ignore the wellbeing of each other and bully every one or we could choose to live in peace with every one and live in peace with them. Society is an important thing. Without order, we could all live in fear as many people try to rule our life. When we are in PSD, our teachers are trying to educate us the important rule of respecting each other and their things. Their things could be anything from their cars to their bodies. We need to treat them as we would like to be treated back. We have all got responsibility to respect each other as we would like to be respected. The Characters involved in the play are: Mr Arthur Birling, Mrs Sybil Birling, Miss Sheila Birling, Master Eric Birling, Mr Gerald Croft, Inspector Goole and Miss Eva Smith Mr Arthur Birling in the play is described as being an arrogant, stubborn man. His view of what had happened to Eva in the play is like he wasn’t interested that a fellow human had died from what he had done. He was more bothered about how he thought the people of Brumley would think of him if they saw the Inspector talk to him about a suicide. He tried, several times in the play, to discourage the Inspector blaming him by saying that he was the Lord Mayor of Brumley or that he is the owner of the company Birling and Co. â€Å"Well I only did what any employer might have done. † I put this in because it shows that Mr Birling is only interested in his business and he’s not interested in any of the workers.

Dams and Reservoirs

Dams and Reservoirs A dam is any barrier that holds back water; dams are primarily used to save, manage, and/or prevent the flow of excess water into specific regions. In addition, some dams are used to generate hydropower. This article examines man-made dams but dams can also be created by natural causes like mass wasting events or even animals like the beaver. Another term often used when discussing dams is reservoir. A reservoir is a man-made lake that is primarily used for storing water. They can also be defined as the specific bodies of water formed by the construction of a dam. For example, the Hetch Hetchy Reservoir in California’s Yosemite National Park is the body of water created and held back by the O’Shaughnessy Dam. Types of Dams One of the most common types of major dams is the arch dam. These masonry or concrete dams are ideal for narrow and/or rocky locations because their curved shape easily holds back water via gravity without the need for a lot of construction materials. Arch dams can have one large single arch or they can have multiple small arches separated by concrete buttresses. The Hoover Dam which is on the border of the U.S. states of Arizona and Nevada is an arch dam. Another type of dam is the buttress dam. These can have multiple arches, but unlike a traditional arch dam, they can be flat as well. Normally buttress dams are made of concrete and feature a series braces called buttresses along the downstream side of the dam to prevent the natural flow of water. The Daniel-Johnson Dam in Quebec, Canada is a multiple arch buttress dam. In the U.S., the most common type of dam is the embankment dam. These are large dams made out of soil and rock which use their weight to hold back water. To prevent water from moving through them, embankment dams also have a thick waterproof core. The Tarbela Dam in Pakistan is the world’s largest embankment dam. Finally, gravity dams are huge dams that are constructed to hold back water using only their own weight. To do this, they are constructed using extensive amounts of concrete, making them difficult and expensive to build. The Grand Coulee Dam in the U.S. state of Washington is a gravity dam. Types of Reservoirs and Construction The first and usually largest type of reservoir is called a valley dammed reservoir. These are reservoirs that are located in narrow valley areas where tremendous amounts of water can be held in by the valley’s sides and a dam. The best location for a dam in these types of reservoirs is where it can be built into the valley wall most effectively to form a water tight seal. To construct a valley dammed reservoir, the river must be diverted, usually through a tunnel, at the start of work. The first step in creating this type of reservoir is the pouring of a strong foundation for the dam, after which construction on the dam itself can begin. These steps can take months to years to complete, depending on the size and complexity of the project. Once finished, the diversion is removed and the river is able to flow freely toward the dam until it gradually fills the reservoir. Dam Controversy In addition, the creation of a reservoir requires the flooding of large areas of land, at the expense of the natural environment and sometimes villages, towns and small cities. The construction of China’s Three Gorges Dam, for example, required the relocation of over one million people and flooded many different archaeological and cultural sites. Main Uses of Dams and Reservoirs Another major use of dams is power generation as hydroelectric power is one of the world’s major sources of electricity. Hydropower is generated when the potential energy of the water on the dam drives a water turbine which in then turns a generator and creates electricity. To best make use of the water’s power, a common type of hydroelectric dam uses reservoirs with different levels to adjust the amount of energy generated as it is needed. When demand is low for instance, water is held in an upper reservoir and as demand increases, the water is released into a lower reservoir where it spins a turbine. Some other important uses of dams and reservoirs include a stabilization of water flow and irrigation, flood prevention, water diversion and recreation. To learn more about dams and reservoirs visit PBSs Dams Site. Rogun - 1,099 feet (335 m) in TajikistanNurek - 984 feet (300 m) in TajikistanGrande Dixence - 932 feet (284 m) in SwitzerlandInguri - 892 feet (272 m) in GeorgiaBoruca - 876 feet (267 m) in Costa RicaVaiont - 860 feet (262 m) in ItalyChicoasà ©n - 856 feet (261 m) in MexicoTehri - 855 feet (260 m) in Indialvaro Abregà ³n - 853 feet (260 m) in MexicoMauvoisin - 820 feet (250 m) in SwitzerlandLake Kariba - 43 cubic miles (180 km ³) in Zambia and ZimbabweKuybyshev Reservoir - 14 cubic miles (58 km ³) in Russia

The Presidential Inaugural Address essays

The Presidential Inaugural Address essays Over the course of the next several months, both presidential nominees will make many speeches in their efforts to campaign for president. However, after the election is overand the last presidential election was not over in the year 2000 until long after Novemberthe president must make an inaugural address in January on the steps of the Capitol building to bring the nation together after a long and divisive campaign. Unlike the campaign speeches, this speech must not be partisan or divisive in the nature of its tone. It must be positive, rather than negative in its use of rhetoric. It must set the stage for the president's entire administration in terms of firmly establishing his vision for the country. It must speak to the world rather than to just the American voters. It must also speak to both houses of congress, republicans and Because of these factors, presidents tend to use poetic and rhetorical tropes when expressing themselves in their inaugural addresses. One of the classic rhetorical uses of antithesis, for example, or the pairing of two unlike ideas with similar phrases is John F. Kennedy's "ask not what your country can do for you, ask what you can do for your country." Note too how Kennedy addresses the young people of the nation, rather than taking any political jibes at his opposition. Even though he was advocating a policy change in terms of creating the Peace Core, he discusses service in positive terms, rather than in the tone of an advocate The president who speaks in January to the nation must speak to a divided nation, frustrated over a protracted Iraqi commitment, higher costs of living in the form of higher oil prices, and a still shaky economy. Whether this president's name is Kerry or Bush, he must inspire the people not simply to believe in him, but to help him heal the nation, the Iraqi ...

My Hangout Fallon Tipton......about skatepark and fall off the board...descriptive

My Hangout Fallon Tipton......about skatepark and fall off the board...descriptive You can hear the sound of the the boards landing on the ground. You can hear the guys there cussing because they are gettin mad at there board. You can hear the sound of someones sound system in their car so they have music to listen too.You get there and you see the regulars there, maybe some newcomers. You see the guys sitting on tables smoking cigarettes. You see the guys out skating doing their tricks. You see the guys "pogo" themselves and get hurt. You may even see someone break a bone or two. Out side of the fence you see guys taking a break and playing basketball.It starts to get cloudy. Then the rains comes. The guys grab their boards and hide under a ramp or to the shelter and wait there until it stops. They close the park. People stay under the shelter just for fun.Some people go home. But in the end it was a good time. Then comes tomorrow.You come tomorrow. You're the only one there. You're board. So you decide to skate by yourself. You're the only girl who tries. You hop e no body will see you if you mess up. You try going down the quarter pipe. You make it all the way down and then you fall. Someone comes in as soon as you fall. They laugh. You laugh. You can barely walk though. Your knee is swolen. It's black and blue already. You dont go home right away and play it off. People yell at you to go put ice on it but you say you'll be fine. After a month from the fall your knee is still screwed up. Maybe you should have went home right away. Oh well...to late now. Your knee will be screwed...

Schema Assignment Example | Topics and Well Written Essays - 250 words - 1

Schema - Assignment Example Nazneen (2009) explains, â€Å"Field type depicts the data type of the field†. For example, a relationship may not be established or may not function correctly if we have selected Number as field type for the primary key attribute and Text field type is selected for the foreign key attribute. A coded field represents a corresponding value stored in a separate relation. Coded fields serve several different purposes, which depends on their implementation. Usually coded fields are introduced to save time and space in RDBMs. Integrity of field ensures entry of predefined data types and formats in an attribute. A user is bound to enter data in correct data type and format while entering using Data Entry Form. There are several tools available, which restricts incorrect data entry or in some cases user can only select from the available list of items / values in a List, Combo, Radio or Checkbox control, etc. Blank or missing fields are those fields where a record does not contain any data. Missing fields can be avoided by introducing compulsory data entry controls, but it is often impossible or undesirable because of user convenience and usability considerations. Missing fields can be populated on-the-fly by default values or in some cases by using auto-increment specification. Normalized tables usually do not translate into efficient physical records because normalization decomposes larger tables into smaller ones and query generates a record based on the unique field in all related tables. Hernandez observes the fact and states, â€Å"The physical order of the record or field in a table is completely immaterial and each record in a table is identified by a field that contains a unique value†

Ethical dilemma essay Example | Topics and Well Written Essays - 500 words

Ethical dilemma - Essay Example Besides, if we pushed the deadline back, we would run the risk of the client withdrawing from the case because his extremely busy schedule might prevent him from attending to the extra paperwork that would be required if the document was to be notarized. I went home that night and thought it over. I knew that since I had my supervisor’s approval, I wouldn’t be held accountable if anything went wrong. However, I believe that as a financial advisor, I had the fiduciary responsibility to ensure that the clients are aware of all aspects of the investments. Also, in order for me to provide my best services, I always try to imagine myself in the situation that my client is in. I knew that if I were the client, I would be extremely disappointed if I found out that my financial services provider treated me as just â€Å"another filed folder† rather than a valued client who deserved the best service possible. The following day, I asked my supervisor to assign the project to me so that I could amend the complication before the deadline. Though unwillingly, my supervisor agreed. I immediately contacted the client, briefed him about the situation, and apologized that due to the prevailing circumstances, we might not be able to make the deadline that he originally set for us.

Nursing theory Essay Example | Topics and Well Written Essays - 1250 words - 1

Nursing theory - Essay Example Orem’s nursing model recognizes universal self-care requirements namely, progressive self-care fundamentals, and health-deviation self- care basics. It evidences in importance of self-care and rehabilitation settings and encourages individual independence during treatments. Hence, self-care incorporates individuals own innovation and suitable implementation strategies for health improvement (Alligood, 2014). If a person takes full responsibility over his or her health, then self-care is achievable. Orem’s self-care theory explains complex interplay of patient’s psychological and socio-economic surroundings on health. Therefore, enlightens individuals to embrace appropriate life styles to minimize lifestyle diseases. Owing to the provisions Orem’s theory, nurse training takes into consideration the changing health care needs and teaches nurses to design issue specific nursing system for care delivery. The principal concepts of the theory identify self-care deficits and characterize individuals and nurse roles in addressing health demands. The components add to the nurses’ career skills to produce and efficiently manage the health scare systems. Therefore, the knowledge base enable nurses to determine extent of self-care need, assist clients to uphold a satisfactory state of self-care determine extent of nursing and utilize theories in practical cases. Since the nursing model centers on individuals capabilities, it helps nurses to conduct and empower people in order to promote healthy living. Dorothy Orem’s self-care system is an excellent education process component that helps students to learn the main health care concepts by examining individuals’ role or enhancing impressions of thought and feelings (Taylor & Renpenning 2011). Largely, the theory aims to overcome human  confines in the provision of nursing services and nursing education programs. The contemporary nursing

Definition of Shame, Unforgettable Shame and Self perception Essay

Definition of Shame, Unforgettable Shame and Self perception - Essay Example Kaufman (1993a, pp.5-6) defines shame as wound within inner self which is deeply disturbing to the self, causing the sickness within the self and the soul which always leads to the feelings of inferiority. This view has been supported in the work of Evans (1994, p.103) who states, â€Å"with shame there is a sense of inferiority in which the other is perceived as more powerful and capable of inflict injury on the self, usually via scorn, contempt, or humiliation†. Jane Middelton-Moz (1990, p.xii) and Holly Vanscoy (2006) both have written that â€Å"the hurt emotion feeling arise from the consciousness of something embarrassment, humiliation, dishonourable, unacceptable, ludicrous etc done by oneself or another†. In my opinion, the individual who faced shame always perceives him or herself as flawed, unwanted, neglected, surplus, or fundamentally broken. Nearly every human being experience shame at some point in his or her life. Most of shame stories in their lives become the unforgettable one. The unforgettable rather haunting shame memory follows people throughout their lives. Shame incident might have happened a long time ago, but memory remains even after years. Sometimes the individual becomes very successful in the country or in the community, but the memory of unforgettable shame keeps clinging to even the developed and successful self. During the research, there were numerous instances when I found a general agreement of psychologists and therapist about the idea that adult personality is greatly influenced by early childhood experiences. Those who experienced shame during early childhood time period could never let their memory of the incident go forever. It remains and leaves extremely powerful impact on adult self perception. For understanding shame in childhood and its manifestation in adulthood in the form of low self-esteem, we need to understand the concept of ‘self’ itself. Self is fundamental part of Carl Rogers’s personality theory. He refers to it as, â€Å"the organized, consistent set of perceptions and beliefs about oneself.†Self is a humanistic term that describes us as person. It is not only influenced by a person’s experiences throughout life but also the interpretation of these experiences. Major factors that influence human self concept are: childhood experiences and evaluation by others (cited in McLeod, 2007). Bradshaw’s idea of a toxic shame seems to be intriguing in this regard. He (1990, p. 47) wrote it as â€Å"the feeling of being flawed and diminished and never measuring up†. The strong inner emotions and feelings of being insufficient, neglected, inadequate, defective and unwanted keep haunting the individual. Bradshaw (1990, p. 47) further attributes the toxic shame as a nucleus of the wounded child around which he or she keeps revolving. For instance, the individual, who faced traumatic or hurtful experience during their childhood which they could not forget all the way through their life are called wounded child and prone to shame. According to Adler, a neglected child has never known love and cooperation in the home; therefore, he finds it very difficult to develop these abilities as an adult. They do not know how to gain affection and respect from other people. As adults usually they are cold and hard (Frager, R. & Fadiman, J., 1998. p. 111-112). The shamed self is considered to be unable to cope with the difficult situation. As an object of scorn, humiliation,

Speech Term Paper Example | Topics and Well Written Essays - 1500 words

Speech - Term Paper Example It will also suggest that the skillful audience analysis employed by President Kennedy shows why audience analysis is important to public speaking in general. The Cuban Missile Crisis Speech: The Right Words at the Last Minute President John F. Kennedy’s speech at the height of the Cuban Missile Crisis was one of the most important speeches in American history. The Soviet Union was building bases in Cuba for nuclear missiles that could reach the United States. Kennedy had to inform the public of the possibility of a Soviet nuclear strike against the United States and simultaneously calm the people’s fears and assure them that everything possible was being done to remedy the situation. He also had to use the opportunity to send a message to Nikita Khrushchev and the leaders of Soviet Union that nuclear bases in Cuba would not be tolerated (Long & Swett, 2010). By closely analyzing this speech, it is possible to see the techniques that Kennedy used to deliver two separate messages to two different audiences at once. In doing this, Kennedy showed the importance of audience analysis in public speaking. Kennedy spoke to two audiences in his speech. The first and most important audience was the American public. The people of the United States had already been worried about the possibility of nuclear war since the end of the Second World War and the start of the Cold War between the United States and the Soviet Union. Kennedy had to deliver accurate news about what was taking place in Cuba and what it meant for America without panicking people. Upon hearing the news, Americans would want to look to a strong leader who had the crisis under control and who would stop the conflict before it spiraled into unthinkable disaster. Because the missiles would be able to reach most of the Western hemisphere, Kennedy’s address held implications for an international audience, as well. The President’s speech also had a secondary purpose. He could also us e the opportunity to make a show of strength to America’s Cold War enemies in the Soviet Union and Cuba. While much of the information delivered in the speech was being exchanged between the powers involved via intelligence, letters, and phone calls, seeing the President proclaim to the American people what strategies would be used against Cuba and the Soviet Union in a speech held more intimidation for the Soviet and Cuban leaders (Bostdorff 1994). A good speech is a powerful emotional tool that can convey the deeper meaning of a message more effectively than a conversation or a written declaration can. Kennedy knew this, and he used the opportunity as a defensive strategy just as much as an informative address. One of the most striking aspects of the speech is the direct and businesslike manner in which Kennedy addresses the American people. To start off, he does not simplify or â€Å"dumb down† the information he conveys, nor does he sugar coat it to make it more pa lletable. Kennedy treats the American people like adults who are capable of understanding the situation. By doing this, he shows the audience that what he’s saying is extremely serious. He then goes on to detail what the Soviet government said about their involvement in the building of the Cuban missile bases and the purpose of these bases, and states emphatically that these assurances were false. Kennedy shows some anger here, but his anger is tightly controlled. By doing this, he

Gender and Marriage in Chinese culture Research Paper

Gender and Marriage in Chinese culture - Research Paper Example Generally, economic development is an umbrella key to understand environmental concern, gender differences in environmentally oriented behaviors, and environmental knowledge. Making use of interview analyses, I identified a pattern of gender differences where women demonstrated a high participation inside home while are concerned with economic role â€Å"Breadwinner† as opposed to environmental issues. Accordingly, gender differences in environmentally oriented patterns could further be understood in family perceptive where children adhere to witness and understand traditional practices. Most Chinese people believed that marriage customs is subject to the pressures of culture. Recently, I interviewed Angie who created great insights on gender and marriage customs in Chinese culture. Angie, 95 is an elderly woman who lives in one of the village in China. She spends most of her life teaching the young generation about the Chinese culture. In fact, she explained that her life exp erience has tremendously increased knowledge of understanding Chinese culture. From her dialogue, I could tell that Angie had profound information about gender issues and marriage customs in her culture. ... Angie continued to explain that women were less privileged in the society and men only counted the number of sons when questioned about the size of their family. Still, some families sold their daughters to wealthy families as slaves. As the Cultural Revolution took hold, Angie explained that women moved into the workforce, but with lower pay rates than men. To date, the Chinese society continues holding men responsible for providing basic needs while women taking care of their households. This discussion is similar to the broader literature of Jin, Li & Feldman (2006, p. 150) who in their research used theoretic perceptive regarding gender and environmental behaviors of Chinese. The study is further supported by Canchu (2010, p. 75) who argues that early childhood interaction render women to being sensitive to the needs of others, thus being more responsible to take on nurturing roles. By contrast, early socialization leads men to great value of achievement and independence. The vie w about interview dissemination created a platform to understand in depth gender issues in the Chinese culture. It is true with regard to Angie argument that women’s greater share of household duties have reduced their availability in the market place. The reverse effect has offset men and women to differ in their levels of contribution in the marketplace and domestic duties. However, Angie claimed that the Chinese government is emphasizing on gender equality as a major constituent of economic development. Following this, she affirmed that women have emerged in the market place to support their families. Overall, Angie created a platform for me to comprehend Chinese marriage ceremonies and customs. She derived her argument from ancient times to make me understand about Chinese

Definition of Shame, Unforgettable Shame and Self perception Essay

Definition of Shame, Unforgettable Shame and Self perception - Essay Example Kaufman (1993a, pp.5-6) defines shame as wound within inner self which is deeply disturbing to the self, causing the sickness within the self and the soul which always leads to the feelings of inferiority. This view has been supported in the work of Evans (1994, p.103) who states, â€Å"with shame there is a sense of inferiority in which the other is perceived as more powerful and capable of inflict injury on the self, usually via scorn, contempt, or humiliation†. Jane Middelton-Moz (1990, p.xii) and Holly Vanscoy (2006) both have written that â€Å"the hurt emotion feeling arise from the consciousness of something embarrassment, humiliation, dishonourable, unacceptable, ludicrous etc done by oneself or another†. In my opinion, the individual who faced shame always perceives him or herself as flawed, unwanted, neglected, surplus, or fundamentally broken. Nearly every human being experience shame at some point in his or her life. Most of shame stories in their lives become the unforgettable one. The unforgettable rather haunting shame memory follows people throughout their lives. Shame incident might have happened a long time ago, but memory remains even after years. Sometimes the individual becomes very successful in the country or in the community, but the memory of unforgettable shame keeps clinging to even the developed and successful self. During the research, there were numerous instances when I found a general agreement of psychologists and therapist about the idea that adult personality is greatly influenced by early childhood experiences. Those who experienced shame during early childhood time period could never let their memory of the incident go forever. It remains and leaves extremely powerful impact on adult self perception. For understanding shame in childhood and its manifestation in adulthood in the form of low self-esteem, we need to understand the concept of ‘self’ itself. Self is fundamental part of Carl Rogers’s personality theory. He refers to it as, â€Å"the organized, consistent set of perceptions and beliefs about oneself.†Self is a humanistic term that describes us as person. It is not only influenced by a person’s experiences throughout life but also the interpretation of these experiences. Major factors that influence human self concept are: childhood experiences and evaluation by others (cited in McLeod, 2007). Bradshaw’s idea of a toxic shame seems to be intriguing in this regard. He (1990, p. 47) wrote it as â€Å"the feeling of being flawed and diminished and never measuring up†. The strong inner emotions and feelings of being insufficient, neglected, inadequate, defective and unwanted keep haunting the individual. Bradshaw (1990, p. 47) further attributes the toxic shame as a nucleus of the wounded child around which he or she keeps revolving. For instance, the individual, who faced traumatic or hurtful experience during their childhood which they could not forget all the way through their life are called wounded child and prone to shame. According to Adler, a neglected child has never known love and cooperation in the home; therefore, he finds it very difficult to develop these abilities as an adult. They do not know how to gain affection and respect from other people. As adults usually they are cold and hard (Frager, R. & Fadiman, J., 1998. p. 111-112). The shamed self is considered to be unable to cope with the difficult situation. As an object of scorn, humiliation,

Gender and Marriage in Chinese culture Research Paper

Gender and Marriage in Chinese culture - Research Paper Example Generally, economic development is an umbrella key to understand environmental concern, gender differences in environmentally oriented behaviors, and environmental knowledge. Making use of interview analyses, I identified a pattern of gender differences where women demonstrated a high participation inside home while are concerned with economic role â€Å"Breadwinner† as opposed to environmental issues. Accordingly, gender differences in environmentally oriented patterns could further be understood in family perceptive where children adhere to witness and understand traditional practices. Most Chinese people believed that marriage customs is subject to the pressures of culture. Recently, I interviewed Angie who created great insights on gender and marriage customs in Chinese culture. Angie, 95 is an elderly woman who lives in one of the village in China. She spends most of her life teaching the young generation about the Chinese culture. In fact, she explained that her life exp erience has tremendously increased knowledge of understanding Chinese culture. From her dialogue, I could tell that Angie had profound information about gender issues and marriage customs in her culture. ... Angie continued to explain that women were less privileged in the society and men only counted the number of sons when questioned about the size of their family. Still, some families sold their daughters to wealthy families as slaves. As the Cultural Revolution took hold, Angie explained that women moved into the workforce, but with lower pay rates than men. To date, the Chinese society continues holding men responsible for providing basic needs while women taking care of their households. This discussion is similar to the broader literature of Jin, Li & Feldman (2006, p. 150) who in their research used theoretic perceptive regarding gender and environmental behaviors of Chinese. The study is further supported by Canchu (2010, p. 75) who argues that early childhood interaction render women to being sensitive to the needs of others, thus being more responsible to take on nurturing roles. By contrast, early socialization leads men to great value of achievement and independence. The vie w about interview dissemination created a platform to understand in depth gender issues in the Chinese culture. It is true with regard to Angie argument that women’s greater share of household duties have reduced their availability in the market place. The reverse effect has offset men and women to differ in their levels of contribution in the marketplace and domestic duties. However, Angie claimed that the Chinese government is emphasizing on gender equality as a major constituent of economic development. Following this, she affirmed that women have emerged in the market place to support their families. Overall, Angie created a platform for me to comprehend Chinese marriage ceremonies and customs. She derived her argument from ancient times to make me understand about Chinese

Biology Lab Essay Example for Free

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A Study On Badrinath Tourism Essay

A Study On Badrinath Tourism Essay Nestled in the shadow of the Nilkantha peak, in the northern Indian state of Uttarakhand, lies one the the most revered shrines for Hindu pilgrims Badrinath. Badrinath is in the Chamoli district of Uttarakhand, in the Garhwal hills, and lies on the banks of the Alakhnanda river. Significance The town of Badrinath has always found a prominent mention in religious Hindu texts and scriptures and was established as a major pilgrimage site in the ninth century by Adi Shankara. Mythology has it that Lord Vishnu had chosen this town for penance to ensure the welfare of all beings. Badrinath is also one of the char dhams (the four abodes) that have tremendous religious significance amongst devout Hindus. Attractions The Badrinath Temple: The temple, built by Adi Shankara, is the prominent attraction of Badrinath and attracts thousands of visitors every year who come to seek the divine blessings of Lord Vishnu. The main shrine houses the balck stone idol of Lord Badrinarayan sitting under a gold canopy, under a Badri tree. Lord Badrinath is the presiding deity but there are several other deities that are worshipped at this temple. Tapt Kund: Believed to be the abode of Agni, the Hindu God of fire, Tapt kund is a thermal spring that devotees take a holy dip before entering the Badrinath temple. The spring is also said to have curative properties.Other famous natural springs that can be found at Badrinath are Narad Kund and Suraj Kund. Brahma Kapal: On the banks of the river Alakhnanda, this is where pilgrims perform rites for their departed near and dear ones. Sheshnetra: This is a rock boulder with an impression of Sheshnag, a mythological serpent. You can also visit Charanpaduka a boulder that bears Lord Vishnus footprints. Alka Puri: Is where the daring tourist goes in search of adventure. This place is famous for white water rafting. Panch Prayag: While in Badrinath, be sure to visit the Panch Prayag, again of religious importance. Devprayag is famous for its rock inscriptions, Rudranath is famous for Chamunda Devi temple, Nandaprayag is known for the Gopalji temple, Karnaprayag for temples of Uma Karna and Vishnuprayag is the place where people flock to visit the Lord Vishnu temple. How to Reach You could fly to Jolly Grant, about 300 km from Badrinath, and then hitch a bus ride to Badrinath. The nearest rail station is Rishikesh which is 297 km from Badrinath. Being a place of religious significance, Badrinath is well connected by road to the tourist spots nearby namely Rishikesh, Haridwar Dheradun from where you could take a bus and ride to Badrinath. We recommend the bus ride as you will get to see breathtaking scenery on the way to Badrinath.

Neurology and Neurosurgery Essay -- Medical Brain Health Essays

Neurology and Neurosurgery Neurology Overview Although our primary interest is with the Medial Temporal Lobe, also called the V5 area, a discussion of the entire motion perception pathway is instructive. Motion perception actually begins with the specialized visual receptors in the retina known as M-cells (from the Latin word magnus, for large). As the name implies, the M-cells are relatively large, located in the peripheral retina, and respond quickly to transient visual stimulation making them ideally suited for motion detection. By contrast, P-cells are smaller, located in the fovea, react more slowly to stimuli, and are suited to fine-detail vision. Impulses from the retina then travel via the optic nerve to the optic chiasm where fibers of the optic nerve from the inner (nasal) half of each retina cross while those from the outside (temporal) half of each retina stay on the same side. This partial crossing is a feature of mammals, whereas for most vertebrates below mammals, all the fibers cross. It must be pointed out that no motion processing is actually done in the optic chiasm. About 20% of the axons leaving the optic chiasm go to the Superior Colliculus, which is responsible for certain eye movements and spatial localization. The remaining 80% of the axons go to the Lateral Geniculate Nucleus, LGN (Schiffman, 2000, p. 71-73). The LGN represents the next motion processing step after the M-cells in the retina. The Magnocellular Division of the LGN specifically processes the impulses from the M- cells in the retina and is uniquely suited to distinguishing small contrasts between light and dark areas thereby enhancing three-dimensionality and motion ef... ..., J. W. (2004). Biological Psychology (8th ed.). Belmont, CA: Thompson-Wadsworth. Naikar, N. (1996). Perception of apparent motion of colored stimuli after commissurotomy. Neuropsychologia, 34(11),1041- 1049. Nawrot, M., Rizzo, M., Rockland, K.S., Howard, M. (2000). A transient deficit of motion perception. Vision Research, (40),3435-3446. Schiffman, H.R. (2000). Sensation and Perception (5th ed.). New York: John Wiley & Sons. Ulbert, I., Karmos, G., Heit, G., & Halgren, E. (2001). Early discrimination of coherent versus incoherent motion by multiunit and synaptic activity in human putative MT+. Human Brain Mapping, 13(4),226-238. Vaina, L.M., Cowey, A., LeMay, M., Bienfang, D.C., & Kikinis, R. (2002). Visual deficits in a patient with kaleidoscopic disintegration of the visual world. European Journal of Neurology, (9),463-477.

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The History and Advantages of High Fructose Corn Syrup HFCS is a popular sweetener used in processed foods. It is composed of approximately 50% fructose and 50% glucose. It is made from corn starch with the use of enzymes to convert glucose to fructose. It has many advantages over cheap sugar, including, but not limited to, lower price, longer shelf life, low freezing point, and enhanced taste and texture. Corn refinement was first discovered circa 1860, and was soon followed by the development of corn syrup. Important advantages took place in the 1920’s with the use of enzymes, but it was not until the mid-1900’s when the crucial glucose isomerase enzyme was discovered. Industrial production of HFCS began in the 1970’s and today the industry is huge. High Fructose Corn Syrup (HFCS) is a sweetener used in many consumer products. Because it is as sweet as sugar, yet cheaper, HFCS is used in many processed food products. Like sugar, it has four calories per gram and has no added artificial or synthetic materials. HFCS is made from corn refinement. First, starch must be separated from the rest of the corn. The starch is then treated with the enzyme glucose isomerase, which converts glucose into fructose. Fructose is an isomer of glucose; both have the empirical formula C6H12O6, but in different bonding. Glucose and fructose bonded together make sucrose, commonly known as table sugar. However, they are found separately in HFCS. Supporters of HFCS claim that it causes no more harm to the body than sugar does because both HFCS and sugar have fructose and glucose in approximately one to one ratios. There are three main types of HFCS: HFCS-42, HFCS-55, HFCS-90. HFCS-42 is 42% fructose and 50% glucose. It is the least sweet of the ... ... Shaft." Freedom Daily Apr. 1998. The Future of Freedom Foundation. 25 July 2006 . Path: James Bovard; FFF articles; The Great Sugar Shaft "Corn Subsidies in United States." Environmental Working Group's Farm Subsidy Database. Nov. 2005. Environmental Working Group. 25 July 2006 . Path: Top Programs; Corn Subsidies. HFCS Facts. 25 July 2006 . "High Fructose Corn Syrup." Learn about Kosher. OU Kosher. 25 July 2006 . "Vignette 4 Bioprocess Engineering for High-Volume Products: The Case of Corn and the Wet-Milling Industry." Putting Biotechnology to Work: Bioprocess Engineering. 1992. 27-29. The National Academic Press. 25 July 2006 .

Ansys Tutorial Release 12.1

 ® ANSYS Tutorial Release 12. 1 Structural & Thermal Analysis Using the ANSYS Release 12. 1 Environment Kent L. Lawrence Mechanical and Aerospace Engineering University of Texas at Arlington SDC PUBLICATIONS www. SDCpublications. com Schroff Development Corporation Visit the following websites to learn more about this book: ANSYS Tutorial 2-1 Lesson 2 Plane Stress Plane Strain 2-1 OVERVIEW Plane stress and plane strain problems are an important subclass of general threedimensional problems. The tutorials in this lesson demonstrate:  ¦Solving planar stress concentration problems. Evaluating potential inaccuracies in the solutions.  ¦Using the various ANSYS 2D element formulations. 2-2 INTRODUCTION It is possible for an object such as the one on the cover of this book to have six components of stress when subjected to arbitrary three-dimensional loadings. When referenced to a Cartesian coordinate system these components of stress are: Normal Stresses ?x, ? y, ? z Shear Stresses ? xy, ? yz, ? zx Figure 2-1 Stresses in 3 dimensions. In general, the analysis of such objects requires three-dimensional modeling as discussed in Lesson 4.However, two-dimensional models are often easier to develop, easier to solve and can be employed in many situations if they can accurately represent the behavior of the object under loading. 2-2 ANSYS Tutorial A state of Plane Stress exists in a thin object loaded in the plane of its largest dimensions. Let the X-Y plane be the plane of analysis. The non-zero stresses ? x, ? y, and ? xy lie in the X – Y plane and do not vary in the Z direction. Further, the other stresses (? z,? yz , and ? zx ) are all zero for this kind of geometry and loading.A thin beam loaded in its plane and a spur gear tooth are good examples of plane stress problems. ANSYS provides a 6-node planar triangular element along with 4-node and 8-node quadrilateral elements for use in the development of plane stress models. We will use both triangles and qua ds in solution of the example problems that follow. 2-3 PLATE WITH CENTRAL HOLE To start off, let’s solve a problem with a known solution so that we can check our computed results as well as our understanding of the FEM process. The problem is that of a tensile-loaded thin plate with a central hole as shown in Figure 2-2.Figure 2-2 Plate with central hole. The 1. 0 m x 0. 4 m plate has a thickness of 0. 01 m, and a central hole 0. 2 m in diameter. It is made of steel with material properties; elastic modulus, E = 2. 07 x 1011 N/m2 and Poisson’s ratio, ? = 0. 29. We apply a horizontal tensile loading in the form of a pressure p = -1. 0 N/m2 along the vertical edges of the plate. Because holes are necessary for fasteners such as bolts, rivets, etc, the need to know stresses and deformations near them occurs very often and has received a great deal of study.The results of these studies are widely published, and we can look up the stress concentration factor for the case s hown above. Before the advent of suitable computation methods, the effect of most complex stress concentration geometries had to be evaluated experimentally, and many available charts were developed from experimental results. The uniform, homogeneous plate above is symmetric about horizontal axes in both geometry and loading. This means that the state of stress and deformation below a Plane Stress / Plane Strain 2-3 orizontal centerline is a mirror image of that above the centerline, and likewise for a vertical centerline. We can take advantage of the symmetry and, by applying the correct boundary conditions, use only a quarter of the plate for the finite element model. For small problems using symmetry may not be too important; for large problems it can save modeling and solution efforts by eliminating one-half or a quarter or more of the work. Place the origin of X-Y coordinates at the center of the hole. If we pull on both ends of the plate, points on the centerlines will move al ong the centerlines but not perpendicular to them.This indicates the appropriate displacement conditions to use as shown below. Figure 2-3 Quadrant used for analysis. In Tutorial 2A we will use ANSYS to determine the maximum horizontal stress in the plate and compare the computed results with the maximum value that can be calculated using tabulated values for stress concentration factors. Interactive commands will be used to formulate and solve the problem. 2-4 TUTORIAL 2A – PLATE Objective: Find the maximum axial stress in the plate with a central hole and compare your result with a computation using published stress concentration factor data.PREPROCESSING 1. Start ANSYS, select the Working Directory where you will store the files associated with this problem. Also set the Jobname to Tutorial2A or something memorable and provide a Title. (If you want to make changes in the Jobname, working Directory, or Title after you’ve started ANSYS, use File > Change Jobname or Di rectory or Title. ) Select the six node triangular element to use for the solution of this problem. 2-4 ANSYS Tutorial Figure 2-4 Six-node triangle. The six-node triangle is a sub-element of the eight-node quadrilateral. 2.Main Menu > Preprocessor > Element Type > Add/Edit/Delete > Add > Structural Solid > Quad 8node 183 > OK Figure 2-5 Element selection. Select the triangle option and the option to define the plate thickness, otherwise a unit thickness is used. 3. Options (Element shape K1) > Triangle, Options (Element behavior K3) > Plane strs w/thk > OK > Close Plane Stress / Plane Strain 2-5 Figure 2-6 Element options. 4. Main Menu > Preprocessor > Real Constants > Add/Edit/Delete > Add > OK Figure 2-7 Real constants. Enter the plate thickness of 0. 01 m. ) >Enter 0. 01 > OK > Close Figure 2-8 Enter the plate thickness. 2-6 ANSYS Tutorial Enter the material properties. 5. Main Menu > Preprocessor > Material Props > Material Models Material Model Number 1, click Structural > Line ar > Elastic > Isotropic Enter EX = 2. 07E11 and PRXY = 0. 29 > OK (Close the Define Material Model Behavior window. ) Create the geometry for the upper right quadrant of the plate by subtracting a 0. 2 m diameter circle from a 0. 5 x 0. 2 m rectangle. Generate the rectangle first. . Main Menu > Preprocessor > Modeling > Create > Areas > Rectangle > By 2 Corners Enter (lower left corner) WP X = 0. 0, WP Y = 0. 0 and Width = 0. 5, Height = 0. 2 > OK 7. Main Menu > Preprocessor > Modeling > Create > Areas > Circle > Solid Circle Enter WP X = 0. 0, WP Y = 0. 0 and Radius = 0. 1 > OK Figure 2-9 Create areas. Plane Stress / Plane Strain 2-7 Figure 2-10 Rectangle and circle. Now subtract the circle from the rectangle. (Read the messages in the window at the bottom of the screen as necessary. ) 8.Main Menu > Preprocessor > Modeling > Operate > Booleans > Subtract > Areas > Pick the rectangle > OK, then pick the circle > OK (Use Raise Hidden and Reset Picking as necessary. ) Figure 2-11 Geo metry for quadrant of plate. Create a mesh of triangular elements over the quadrant area. 9. Main Menu > Preprocessor > Meshing > Mesh > Areas > Free Pick the quadrant > OK Figure 2-12 Triangular element mesh. Apply the displacement boundary conditions and loads to the geometry (lines) instead of the nodes as we did in the previous lesson.These conditions will be applied to the FEM model when the solution is performed. 10. Main Menu > Preprocessor > Loads > Define Loads > Apply > Structural > Displacement > On Lines Pick the left edge of the quadrant > OK > UX = 0. > OK 2-8 ANSYS Tutorial 11. Main Menu > Preprocessor > Loads > Define Loads > Apply > Structural > Displacement > On Lines Pick the bottom edge of the quadrant > OK > UY = 0. > OK Apply the loading. 12. Main Menu > Preprocessor > Loads > Define Loads > Apply > Structural > Pressure > On Lines.Pick the right edge of the quadrant > OK > Pressure = -1. 0 > OK (A positive pressure would be a compressive load, so we use a nega tive pressure. The pressure is shown by the two arrows. ) Figure 2-13 Model with loading and displacement boundary conditions. The model-building step is now complete, and we can proceed to the solution. First, to be safe, save the model. 13. Utility Menu > File > Save as Jobname. db (Or Save as †¦. ; use a new name) SOLUTION The interactive solution proceeds as illustrated in the tutorials of Lesson 1. 14. Main Menu > Solution > Solve > Current LS > OKThe /STATUS Command window displays the problem parameters and the Solve Current Load Step window is shown. Check the solution options in the /STATUS window and if all is OK, select File > Close In the Solve Current Load Step window, select OK, and when the solution is complete, Close the ‘Solution is Done! ’ window. POSTPROCESSING We can now plot the results of this analysis and also list the computed values. First examine the deformed shape. 15. Main Menu > General Postproc > Plot Results > Deformed Shape > Def. + Undef. > OK Plane Stress / Plane Strain 2-9 Figure 2-14 Plot of Deformed shape.The deformed shape looks correct. (The undeformed shape is indicated by the dashed lines. ) The right end moves to the right in response to the tensile load in the X direction, the circular hole ovals out, and the top moves down because of Poisson’s effect. Note that the element edges on the circular arc are represented by straight lines. This is an artifact of the plotting routine not the analysis. The six-node triangle has curved sides, and if you pick on a mid-side of one these elements, you will see that a node is placed on the curved edge. The maximum displacement is shown on the graph legend as 0. 2e-11 which seems reasonable. The units of displacement are meters because we employed meters and N/m2 in the problem formulation. Now plot the stress in the X direction. 16. Main Menu > General Postproc > Plot Results > Contour Plot > Element Solu > Stress > X-Component of stress > OK Use PlotCtrls > Symbols [/PSF] Surface Load Symbols (set to Pressures) and Show pre and convect as (set to Arrows) to display the pressure loads. Figure 2-15 Surface load symbols. Also select Display All Applied BCs 2-10 ANSYS Tutorial Figure 2-16 Element SX stresses.The minimum, SMN, and maximum, SMX, stresses as well as the color bar legend give an overall evaluation of the ? x (SX) stress state. We are interested in the maximum stress at the hole. Use the Zoom to focus on the area with highest stress. (Your meshes and results may differ a bit from those shown here. ) Figure 2-17 SX stress detail. Plane Stress / Plane Strain 2-11 Stress variations in the actual isotropic, homogeneous plate should be smooth and continuous across elements. The discontinuities in the SX stress contours above indicate that the number of elements used in this model is oo few to calculate with complete accuracy the stress values near the hole because of the stress gradients there. We will not accept this stress solu tion. More six-node elements are needed in the region near the hole to find accurate values of the stress. On the other hand, in the right half of the model, away from the stress riser, the calculated stress contours are smooth, and SX would seem to be accurately determined there. It is important to note that in the plotting we selected Element Solu (Element Solution) in order to look for stress contour discontinuities.If you pick Nodal Solu to plot instead, for problems like the one in this tutorial, the stress values will be averaged before plotting, and any contour discontinuities (and thus errors) will be hidden. If you plot nodal solution stresses you will always see smooth contours. A word about element accuracy: The FEM implementation of the truss element is taken directly from solid mechanics studies, and there is no approximation in the solutions for node-loaded truss structures formulated and solved in the ways discussed in Lesson 1.The continuum elements such as the ones for plane stress and plane strain, on the other hand, are normally developed using displacement functions of a polynomial type to represent the displacements within the element, and the higher the polynomial, the greater the accuracy. The ANSYS six-node triangle uses a quadratic polynomial and is capable of representing linear stress and strain variations within an element. Near stress concentrations the stress gradients vary quite sharply. To capture this variation, the number of elements near the stress concentrations must be increased proportionately.To obtain more elements in the model, return to the Preprocessor and refine the mesh, first remove the pressure. All elements are subdivided and the mesh below is created 17. Main Menu > Preprocessor > Loads > Define Loads > Delete > Structural > Pressure > On Lines. Pick the right edge of the quadrant. Main Menu > Preprocessor > Meshing > Modify Mesh > Refine At > All (Select Level of refinement 1. ) Figure 2-18 Global mesh refineme nt. 2-12 ANSYS Tutorial We will also refine the mesh selectively near the hole. 18.Main Menu > Preprocessor > Meshing > Modify Mesh > Refine At > Nodes. (Select the three nodes shown. ) > OK (Select the Level of refinement = 1) > OK Figure 2-19 Selective refinement at nodes. (Note: Alternatively you can use Preprocessor > Meshing > Clear > Areas to remove all elements and build a completely new mesh. Plot > Areas afterwards to view the area again. Note also that too much local refinement can create a mesh with too rapid a transition between fine and coarse mesh regions. ) Reapply the pressure loading, repeat the solution, and replot the stress SX. 9. Main Menu > Solution > Solve > Current LS > OK Save your work. 20. File > Save as Jobname. db Plot the stresses in the X direction. 21. Main Menu > General Postproc > Plot Results > Contour Plot > Element Solu > Stress > X-Component of stress > OK Plane Stress / Plane Strain 2-13 Figure 2-20 SX stress contour after mesh refinement. Figu re 2-21 SX stress detail contour after mesh refinement. The element solution stress contours are now smooth across element boundaries, and the stress legend shows a maximum value of 4. 386 Pa, a 4. percent change in the SX stress computed using the previous mesh. To check this result, find the stress concentration factor for this problem in a text or reference book or from a suitable web site. For the geometry of this example we find Kt = 2. 17. We can compute the maximum stress using (Kt)(load)/(net cross sectional area). Using the pressure p = 1. 0 Pa we obtain. ? x MAX = 2. 17 * p * (0. 4)(0. 01) /[(0. 4 ? 0. 2) * 0. 01] = 4. 34 Pa 2-14 ANSYS Tutorial The computed maximum value is 4. 39 Pa which is around one percent in error, assuming that the value of Kt is exact. -5 THE APPROXIMATE NATURE OF FEM As mentioned above, the stiffness matrix for the truss elements of Lesson 1 can be developed directly and simply from elementary solid mechanics principles. For continuum problems in t wo and three-dimensional stress, this is generally no longer possible, and the element stiffness matrices are usually developed by assuming something specific about the characteristics of the displacements that can occur within an element. Ordinarily this is done by specifying the highest degree of the polynomial that governs the displacement distribution within an element.For h-method elements, the polynomial degree depends upon the number of nodes used to describe the element, and the interpolation functions that relate displacements within the element to the displacements at the nodes are called shape functions. In ANSYS, 2-dimensional problems can be modeled with six-node triangles, four-node quadrilaterals or eight-node quadrilaterals. Figure 2-22 Triangular and quadrilateral elements. The greater the number of nodes, the higher the order of the polynomial and the greater the accuracy in describing displacements, stresses and strains within the element. If the stress is constan t throughout a region, a very imple model is sufficient to describe the stress state, perhaps only one or two elements. If there are gradients in the stress distributions within a region, high-degree displacement polynomials and/or many elements are required to accurately analyze the situation. These comments explain the variation in the accuracy of the results as different numbers of elements were used to solve the problem in the previous tutorial and why the engineer must carefully prepare a model, start with small models, grow the models as understanding of the problem develops and carefully interpret the calculated results.The ease with which models can be prepared and solved sometimes leads to careless evaluation of the computed results. Plane Stress / Plane Strain 2-15 2-6 ANSYS FILES The files created during the solution were saved in step 20 of Tutorial 2A. Look in the working directory and you see Tutorial2A files with extensions BCS, db, dbb, esav, full, mntr, rst, and sta t. However, the Tutorial 2A problem can be reloaded using only Tutorial2A. db, so if you want to save disk space, you can delete the others. 2-7 ANSYS GEOMETRY The finite element model consists of elements and nodes and is separate from the geometry on which it may be based.It is possible to build the finite element model without consideration of any underlying geometry as was done in the truss examples of Lesson 1, but in many cases, development of the geometry is the first task. Two-dimensional geometry in ANSYS is built from keypoints, lines (straight, arcs, splines), and areas. These geometric items are assigned numbers and can be listed, numbered, manipulated, and plotted. The keypoints (2,3,4,5,6), lines (2,3,5,9,10), and area (3) for Tutorial 2A are shown below. (Your numbering may differ. ) Figure 2-23 Keypoints, lines and areas.The finite element model developed previously for this part used the area A3 for development of the node/element FEM mesh. The loads, displacement b oundary conditions and pressures were applied to the geometry lines. When the solution step was executed, the loads were transferred from the lines to the FEM model nodes. Applying boundary conditions and loads to the geometry facilitates remeshing the problem. The geometry does not change, only the number and location of nodes and elements, and at solution time, the loads are transferred to the new mesh.Geometry can be created in ANSYS interactively (as was done in the previous tutorial) or it can be created by reading a text file. For example, the geometry of Tutorial 2A can be generated with the following text file using the File > Read Input from command sequence. (The keypoint, line, etc. numbers will be different from those shown above. ) 2-16 ANSYS Tutorial /FILNAM,Geom /title, Stress Concentration Geometry ! Example of creating geometry using keypoints, lines, arcs /prep7 ! Create geometry k, 1, 0. 0, 0. 0 ! Keypoint 1 is at 0. 0, 0. 0 k, 2, 0. 1, 0. 0 , 3, 0. 5, 0. 0 k, 4, 0. 5, 0. 2 k, 5, 0. 0, 0. 2 k, 6, 0. 0, 0. 1 L, L, L, L, 2, 3, 4, 5, 3 4 5 6 ! Line from keypoints 2 to 3 ! arc from keypoint 2 to 6, center kp 1, radius 0. 1 LARC, 2, 6, 1, 0. 1 AL, 1, 2, 3, 4, 5 ! Area defined by lines 1,2,3,4,5 Geometry for FEM analysis also can be created with solid modeling CAD or other software and imported into ANSYS. The IGES (Initial Graphics Exchange Specification) neutral file is a common format used to exchange geometry between computer programs. Tutorial 2B demonstrates this option for ANSYS geometry development. -8 TUTORIAL 2B – SEATBELT COMPONENT Objective: Determine the stresses and deformation of the prototype seatbelt component shown in the figure below if it is subjected to tensile load of 1000 lbf. Figure 2-24 Seatbelt component. The seatbelt component is made of steel, has an over all length of about 2. 5 inches and is 3/32 = 0. 09375 inches thick. A solid model of the part was developed in a CAD system and exported as an IGES file. The f ile is imported into ANSYS for analysis. For simplicity we will analyze only the right, or ‘tongue’ portion of the part in this tutorial.Plane Stress / Plane Strain 2-17 Figure 2-25 Seatbelt ‘tongue’. PREPROCESSING 1. Start ANSYS, Run Interactive, set jobname, and working directory. Create the top half of the geometry above. The latch retention slot is 0. 375 x 0. 8125 inches and is located 0. 375 inch from the right edge. If you are not using an IGES file to define the geometry for this exercise, you can create the geometry directly in ANSYS with key points, lines, and arcs by selecting File > Read Input from to read in the text file given below and by skipping the IGES import steps 2, 3, 4, and 10 below. FILNAM,Seatbelt /title, Seatbelt Geometry ! Example of creating geometry using keypoints, lines, arcs /prep7 ! Create geometry k, 1, 0. 0, 0. 0 ! Keypoint 1 is at 0. 0, 0. 0 k, 2, 0. 75, 0. 0 k, 3, 1. 125, 0. 0 k, 4, 1. 5, 0. 0 k, 5, 1. 5, 0. 5 k, 6, 1. 2 5, 0. 75 k, 7, 0. 0, 0. 75 k, 8, 1. 125, 0. 375 k, 9, 1. 09375, 0. 40625 k, 10, 0. 8125, 0. 40625 k, 11, 0. 75, 0. 34375 k, 12, 1. 25, 0. 5 k, 13, 1. 09375, 0. 375 k, 14, 0. 8125, 0. 34375 2-18 L, L, L, L, L, L, L, L, ANSYS Tutorial 1, 2 3, 4 4, 5 6, 7 7, 1 3, 8 9, 10 11, 2 ! arc LARC, LARC, LARC, Line from keypoints 1 to 2 from keypoint 5 to 6, center kp 12, radius 0. 25, etc. 5,6, 12, 0. 25 8, 9, 13, 0. 03125 10, 11, 14, 0. 0625 AL,all ! Use all lines to create the area. 2. Alternatively, use a solid modeler to create the top half of the component shown above in the X-Y plane and export an IGES file of the part. To import the IGES file 3. Utility Menu > File > Import > IGES Select the IGES file you created earlier. Accept the ANSYS import default settings. If you have trouble with the import, select the alternate options and try again.Defeaturing is an automatic process to remove inconsistencies that may exist in the IGES file, for example lines that, because of the modeling or th e file translation process, do not quite join to digital precision accuracy. Figure 2-26 IGES import. Turn the IGES solid model around if necessary so you can easily select the X-Y plane. Plane Stress / Plane Strain 2-19 4. Utility Menu > PlotCtrls > Pan, Zoom, Rotate > Back, or use the side-bar icon. Figure 2-27 Seatbelt solid, front and back. 5.Main Menu > Preprocessor > Element Type > Add/Edit/Delete > Add > Solid > Quad 8node 183 > OK (Use the 8-node quadrilateral element for this problem. ) 6. Options > Plane strs w/thk > OK > Close Enter the thickness 7. Main Menu > Preprocessor > Real Constants > Add/Edit/Delete > Add > (Type 1 Plane 183) > OK > Enter 0. 09375 > OK > Close Enter the material properties 8. Main Menu > Preprocessor > Material Props > Material Models Material Model Number 1, click Structural > Linear > Elastic > Isotropic Enter EX = 3. 0E7 and PRXY = 0. > OK (Close Define Material Model Behavior window. ) Now mesh the X-Y plane area. (Turn on area numbers if it helps. ) 9. Main Menu > Preprocessor > Meshing > Mesh > Areas > Free. Pick the X-Y planar area > OK IMPORTANT NOTE: The mesh below was developed from an IGES geometry file. Using the text file geometry definition, may produce a much different mesh. If so, use the Modify Mesh refinement tools to obtain a mesh density that produces results with accuracies comparable to those given below. Computed stress values can be surprisingly sensitive to mesh differences. -20 ANSYS Tutorial Figure 2-28 Quad 8 mesh. The IGES solid model is no longer needed, and since its lines and areas may interfere with subsequent modeling operations, we can delete it from the session. 10. Main Menu > Preprocessor > Modeling > Delete > Volume and Below (Don’t be surprised if everything disappears. Just Plot > Elements to see the mesh again. ) 11. Utility Menu > PlotCtrls > Pan, Zoom, Rotate > Front front side of mesh. ) (If necessary to see the Figure 2-29 . Mesh, front view. Now apply displacement and pr essure boundary conditions.Zero displacement UX along left edge and zero UY along bottom edge. 12. Main Menu > Preprocessor > Loads > Define Loads > Apply > Structural > Displacement > On Lines Pick the left edge > UX = 0. > OK 13. Main Menu > Preprocessor > Loads > Define Loads > Apply > Structural > Displacement > On Lines Pick the lower edge > UY = 0. > OK The 1000 lbf load corresponds to a uniform pressure of about 14,000 psi along the ? inch vertical inside edge of the latch retention slot. [1000 lbf/(0. 09375 in. x 0. 75 in. )]. 14.Main Menu > Preprocessor > Loads > Define Loads > Apply > Structural > Pressure > On Lines Plane Stress / Plane Strain 2-21 Select the inside line and set pressure = 14000 > OK Figure 2-30 Applied displacement and pressure conditions. Solve the equations. SOLUTION 15. Main Menu > Solution > Solve > Current LS > OK POSTPROCESSING Comparing the von Mises stress with the material yield stress is an accepted way of evaluating static load yielding for du ctile metals in a combined stress state, so we enter the postprocessor and plot the element solution of von Mises stress, SEQV. 16.Main Menu > General Postproc > Plot Results > Contour Plot > Element Solu > Stress > (scroll down) von Mises > OK Zoom in on the small fillet where the maximum stresses occur. The element solution stress contours are reasonably smooth, and the maximum von Mises stress is around 118,000 psi. Further mesh refinement gives a stress value of approximately 140,000 psi. The small fillet radius of this geometry illustrates the challenges that can arise in creating accurate solutions, however you can easily come within a few percent of the most likely true result using the methods discussed thus far.Figure 2-31 Von Mises stresses. 2-22 ANSYS Tutorial Redesign to reduce the maximum stress requires an increase in the thickness or fillet radius. Look at charts of stress concentration factors, and you notice that the maximum stress increases as the radius of the str ess raiser decreases, approaching infinite values at zero radii. If your model has a zero radius notch, your finite-size elements will show a very high stress but not infinite stress. If you refine the mesh, the stress will increase but not reach infinity.The finite element technique necessarily describes finite quantities and cannot directly treat an infinite stress at a singular point, so don’t ‘chase a singularity’. If you do not care what happens at the notch (static load, ductile material, etc. ) do not worry about this location but examine the stresses and strains in other regions. If you really are concerned about the maximum stress in a particular location (fatigue loads or brittle material), then use the actual part notch radius however small (1/32 for this tutorial); do not use a zero radius.Also examine the stress gradient in the vicinity of the notch to make sure the mesh is sufficiently refined near the notch. If a crack tip is the object of the anal ysis, you should look at fracture mechanics approaches to the problem. (See ANSYS help topics on fracture mechanics. ) The engineer’s responsibility is not only to build useful models, but also to interpret the results of such models in intelligent and meaningful ways. This can often get overlooked in the rush to get answers. Continue with the evaluation and check the strains and deflections for this model as well. 7. Main Menu > General Postproc > Plot Results > Contour Plot > Element Solu > Strain-total > 1st prin > OK The maximum principal normal strain value is found to be approximately 0. 004 in/in. 18. Main Menu > General Postproc > Plot Results > Contour Plot > Nodal Solu > DOF Solution > X-Component of displacement > OK Figure 2-32 UX displacements. Plane Stress / Plane Strain 2-23 The maximum deflection in the X direction is about 0. 00145 inches and occurs as expected at the center of the right-hand edge of the latch retention slot. -9 MAPPED MESHING Quadrilateral m eshes can also be created by mapping a square with a regular array of cells onto a general quadrilateral or triangular region. To illustrate this, delete the last line, AL,all, from the text file above so that the area is not created (just the lines) and read it into ANSYS. Use PlotCtrls to turn Keypoint Numbering On. Then use 1. Main Menu > Preprocessor > Modeling > Create > Lines > Lines > Straight Line. Successively pick pairs of keypoints until the four interior lines shown below are created. Figure 2-33 Lines added to geometry. 2.Main Menu > Preprocessor > Modeling > Create > Areas > Arbitrary > By Lines Pick the three lines defining the lower left triangular area. > Apply > Repeat for the quadrilateral areas. > Apply > OK Figure 2-34 Quadrilateral/Triangular regions. 3. Main Menu > Preprocessor > Modeling > Operate > Booleans > Glue > Areas > Pick All 2-24 ANSYS Tutorial The glue operation preserves the boundaries between areas that we will need for mapped meshing. 4. Main Men u > Preprocessor > Meshing > Size Cntrls > ManualSize > Lines > All Lines Enter 4 for NDIV, No. lement divisions > OK All lines will be divided into four segments for mesh creation. Figure 2-35 Element size on picked lines. 5. Main Menu > Preprocessor > Element Type > Add/Edit/Delete > Add > Solid > Quad 8node 183 > OK (Use the 8-node quadrilateral element for the mesh. ) 6. Main Menu > Preprocessor > Meshing > Mesh > Areas > Mapped > 3 or 4 sided > Pick All The mesh below is created. Applying boundary and load conditions and solving gives the von Mises stress distribution shown.The stress contours are discontinuous because of the poor mesh quality. Notice the long and narrow quads near the point of maximum stress. We need more elements and they need to be better shaped with smaller aspect ratios to obtain satisfactory results. Plane Stress / Plane Strain 2-25 Figure 2-36 Mapped mesh and von Mises results. One can tailor the mapped mesh by specifying how many elements are to be plac ed along which lines. This allows much better control over the quality of the mesh, and an example of using this approach is described in Lesson 4. 2-10 CONVERGENCEThe goal of finite element analysis as discussed in this lesson is to arrive at computed estimates of deflection, strain and stress that converge to definite values as the number of elements in the mesh increases, just as a convergent series arrives at a definite value once enough terms are summed. For elements based on assumed displacement functions that produce continuum models, the computed displacements are smaller in theory than the true displacements because the assumed displacement functions place an artificial constraint on the deformations that can occur.These constraints are relaxed as the element polynomial is increased or as more elements are used. Thus your computed displacements usually converge smoothly from below to fixed values. Strains are the x and/or y derivatives of the displacements and thus depend o n the distribution of the displacements for any given mesh. The strains and stresses may change in an erratic way as the mesh is refined, first smaller than the final computed values, then larger, etc. Not all elements are developed using the ideas discussed above, and some will give displacements that converge from above. (See Lesson 6. In any case you should be alert to computed displacement and stress variations as you perform mesh refinement during the solution of a problem. 2-11 TWO-DIMENSIONAL ELEMENT OPTIONS The analysis options for two-dimensional elements are: Plane Stress, Axisymmetric, Plane Strain, Plane Stress with Thickness and Generalized Plane Strain. The two examples thus far in this lesson were of the third type, namely problems of plane stress in which we provided the thickness of the part. 2-26 ANSYS Tutorial The first analysis option, Plane Stress, is the ANSYS default and provides an analysis for a part with unit thickness.If you are working on a design problem in which the thickness is not yet known, you may wish to use this option and then select the thickness based upon the stress, strain, and deflection distributions found for a unit thickness. The second option, Axisymmetric analysis is covered in detail in Lesson 3. Plane Strain occurs in a problem such as a cylindrical roller bearing caged against axial motion and uniformly loaded in a direction normal to the cylindrical surface. Because there is no axial motion, there is no axial strain.Each slice through the cylinder behaves like every other and the problem can be conveniently analyzed with a planar model. Another plane strain example is that of a long retaining wall, restrained at each end and loaded uniformly by soil pressure on one or both faces. The Generalized Plane Strain feature assumes a finite deformation domain length in the Z direction, as opposed to the infinite value assumed for standard plane strain. 2-12 SUMMARY Problems of stress concentration in plates subject to in-plane loadings were used to illustrate ANSYS analysis of plane stress problems.Free triangular and quadrilateral element meshes were developed and analyzed. Mapped meshing with quads was also presented. Similar methods are used for solving problems involving plane strain; one only has to choose the appropriate option during element selection. The approach is also applicable to axisymmetric geometries as discussed in the next lesson. 2-13 PROBLEMS In the problems below, use triangular and/or quadrilateral elements as desired. Triangles may produce more regular shaped element meshes with free meshing.The six-node triangles and eight-node quads can approximate curved surface geometries and, when stress gradients are present, give much better results than the four-node quad elements. 2-1 Find the maximum stress in the aluminum plate shown below. Use tabulated stress concentration factors to independently calculate the maximum stress. Compare the two results by determining the percen t difference in the two answers. Convert the 12 kN concentrated force into an equivalent pressure applied to the edge. Plane Stress / Plane Strain 2-27 Figure P2-1 -2 Find the maximum stress for the plate from 2-1 if the hole is located halfway between the centerline and top edge as shown. You will now need to model half of the plate instead of just one quarter and properly restrain vertical rigid body motion. One way to do this is to fix one keypoint along the centerline from UY displacement. Figure P2-2 2-28 ANSYS Tutorial 2-3 An aluminum square 10 inches on a side has a 5-inch diameter hole at the center. The object is in a state of plane strain with an internal pressure of 1500 psi. Determine the magnitude and location of the maximum principal stress, the maximum rincipal strain, and the maximum von Mises stress. Note that no thickness need be supplied for plane strain analysis. Figure P2-3 2-4 Repeat 2-3 for a steel plate one inch thick in a state of plane stress. 2-5 See if yo u can reduce the maximum stress for the plate of problem 2-1 by adding holes as shown below. Select a hole size and location that you think will smooth out the ‘stress flow’ caused by the load transmission through the plate. Figure P2-5 2-6 Repeat 2-1 but the object is now a plate with notches or with a step in the geometry. (See the next figure. ) Select your own dimensions, materials, and loads.Use published stress concentration factor data to compare to your results. The published results are for plates that are relatively long so that there is a uniform state of axial stress at either end relatively far from notch or hole. Create your geometry accordingly. Plane Stress / Plane Strain 2-29 Figure P2-6 2-7 Solve the seatbelt component problem of Tutorial 2B again using six node triangular elements instead of the quadrilaterals. Experiment with mesh refinement. Turn on Smart Sizing using size controls to examine the effect on the solution. See if you can compute a maxi mum von Mises stress of around 140 kpsi. -8 Determine the stresses and deflections in an object ‘at hand’ (such as a seatbelt tongue or retaining wall) whose geometry and loading make it suitable for plane stress or plane strain analysis. Do all the necessary modeling of geometry (use a CAD system if you wish), materials and loadings. 2-9 A cantilever beam with a unit width rectangular cross section is loaded with a uniform pressure along its upper surface. Model the beam as a problem in plane stress. Compute the end deflection and the maximum stress at the cantilever support. Compare your results to those you would find using elementary beam theory.Figure P2-8 Restrain UX along the cantilever support line, but restrain UY at only one keypoint along this line. Otherwise, the strain in the Y direction due to the Poisson effect is prevented here, and the root stresses are different from elementary beam theory because of the singularity created. (Try fixing all node points in UX and UY and see what happens. ) Select your own dimensions, materials, and pressure. Try a beam that’s long and slender and one that’s short and thick. The effect of shear loading becomes more important in the deflection analysis as the slenderness decreases.