History and Advantages of High Fructose Corn Syrup Essay -- Artificial

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.

Investigation of Failed States & Democratic Intervention Essay

Failed states have been an issue in human society for many years. Today there are a total of 177 failed states, which is an all-time high. (Haken) Failed states are not only a terrible situation for the country itself, but for its neighboring countries as well. Some situations are worse than others, but for the most part they all share several factors that classify them as failed states. These factors include a severe economic decline, lack of formal government, deterioration of public services, social disorder, and more. (Haken) Once a country becomes classified as a failed state it is quite difficult for them to fully recover. For this to happen, assistance from allies and neighboring countries is usually necessary. Obviously nobody wants to see a country’s government overrun and its citizens forced into turmoil, but that is unfortunately the way our society operates with radical militant groups such as Al-Qaeda in existence. It has become a global problem and the day may never come when there are no failed states. However, if groups such as Al-Qaeda and the Lord’s Resistance Army (LRA) can be eliminated then these failed states can begin to rebuild themselves and give their citizens the chance to live free, happy lives. An example of a failed state that is making headlines these days is the country of Mali, which is located in Northern Africa. The situation in Mali began over a year ago and has developed into a very serious matter. Much like Libya in 2011, Mali’s government has been overthrown by Islamic militant groups that will do whatever it takes to spread their influence and power. (Larison) The major group behind this invasion is known as Al-Qaeda. As Al-Qaeda forces moved in on Bamako, Mali’s capital, a French military invasion halted them in their tracks. French and Malian forces have now teamed up against â€Å"Al-Qaeda in Islamic Maghreb† (AQIM), which is Al-Qaeda’s militant organization based in Mali. (Larison) The two sides are both ready to battle one another and the situation looks to be headed towards a full-on war. AQIM forces are invading towns and villages while torturing and killing citizens in their path. They are a strong force to be reckoned with and outside help will be needed if Mali is to rid itself of these radicals. This is where neighboring countries become involved. Countries close to Mali, such as Niger, Mauritania, and Algeria, are all looked upon to intervene and to offer aid and/or assistance to the Malians. On top of that, they are forced to live under constant fear and uncertainty of AQIM’s next move(s). Although the United States has no vital economic ties to Mali, some Americans feel obligated to intervene and offer assistance to the French, much like we did in Libya. (Larison) However, the majority of American politicians are against issuing an invasion because all signs point towards an ongoing war similar to those in Iraq and Afghanistan. These two countries experienced this type of situation during the 2000s and Libya did as well in 2011. Libya’s situation was very similar to that of Mali’s current one. Islamic forces invaded and took control and outside help was needed from either neighboring countries or Western forces. Whatever the case may be, many parties were/are involved and too many unnecessary deaths have been recorded already. Going forward we can only hope that the situation in Mali ends up like the ones in Iraq and Libya. The only way this can happen is if the Islamic militant forces are driven out and the country has the opportunity to once again govern itself and eventually prosper. Western intervention has been a major component of global warfare for the last 100 years. From World War I all the way through the Cold War, the United States has always been looked upon to give military assistance to its allies and anyone who holds great importance to our economy. Most recently we’ve gone to war to protect Israel in the Middle East and to aid France in Libya. (Traub) The United States has been involved economically in the Middle East since the late 1980s but became active militarily in 2001 after the 9/11 attacks. We were involved in warfare with Iraq for over a decade and are still at war with Afghanistan. (Traub) Other notable instances of Western military intervention include our involvement in World Wars I and II, the Korean War, the Vietnam War, the Cold War, and many other smaller wars. The United States has clearly played a crucial role in global warfare for a very long time. One major reason for this amount of military activity is the fact that the U.S. is a democracy. Non-democracy governments typically have less involvement in warfare than democratic governments do. This is because autocracies operate under the discretion of less than 20 people and often times only 1 person. Also, under a democracy a presidential order can be overturned by either the citizens or another branch of the government. A democratic leader would most likely order a military invasion if there is an immediate threat to his/her country’s national security or if there is a very significant amount of economic importance involved in the situation. Giving assistance to allies is also a common reason for entering into a war. These have been the main reasons for American involvement in global warfare over the years. America is undoubtedly a military superpower in the eyes of the world and will most likely remain that way for many more years to come. Works Cited Haken, Nate. â€Å"Interpreting the Arab Spring and Its Effects.† Fundforpeace.org. The Fund for Peace, 28 June 2012. Web. 22 Jan. 2013. . Larison, Daniel. â€Å"In Mali the Domino Theory Is Real.† Theamericanconservative.com. The American Conservative, 23 Jan. 2013. Web. 24 Jan. 2013. . Traub, James. â€Å"Think Again: Failed States.† Foreign Policy Magazine, Aug. 2011. Web. 22 Jan. 2013. .

General Motors Article Example | Topics and Well Written Essays - 750 words

General Motors - Article Example Bowen and Radhakrishna (1991) define motivation as a force that makes an organism or a person to respond. Thus an effective manager must be aware of the various factors that induce his or her employees to behave in a certain way. One of the significance theories that early managers adopted in their management was related to the appetitive function. According to this theory, the result of motivated employees which is the outcome of the forces and stimulus provided by the employers is brought about by imagination, memory as well as perception.According to James (2010) in his article on understanding employee’s motivation, staffs are not only motivated by salary increment but also by other factors such as more responsibilities, training, and shifts among others. Additionally, James (2010) covers the Hawthorne studies that sought to indicate the significance of human relations to the managers especially in focusing at the motivation and the needs of the employees. Two major ways t hat GM can emulate to maintain a productive work force is through provision of extrinsic and intrinsic motivators. Intrinsic factors include recognition of the hard working employees. This may be undertaken by promoting them or making them to be team leaders. On the other hard, James (2010) argues that a firm can provide job security and increased salaries as key extrinsic factors. James depicts that managers should also ensure equity among the employees as a way of motivating them. Equity is attained when the ratio of a worker’s output over inputs is the same with that of other employees (James, 2010). Studies undertaken by Adams (1965) indicate that for managers to effectively motivate their employees, it is paramount to first understand their goals. This is based on the fact that the goals of the employees vary. Through the provision of hygiene factors that include security, safety, salary, fringe benefits among others Adams (1965) argues that employees are powerfully motivated. Thus it is paramount for the GM managers to determine what their employees like and dislike so as to identify the appropriate hygiene factor to emulate. Adams (1965) argues that employees like six major aspect to improve their performance. First is achievement. This implies that workers are motivated when tangible goals are derived from their efforts. Secondly, employees like to be appreciated and recognized by their managers and other workers. Thirdly, employees are motivated by the work itself. For example, employees who enjoy working in garages will be more motivated if the GM managers take them to the production facility. Fourthly, workers are motivated when their responsibilities are increased. Fifthly, labor force is significantly motivated through promotion and advancement within their firm. In the same way, workers performance is enhanced when a company creates opportunities for growth. This can be undertaken by ensuring that workers are given ample opportunities to undertake part time courses either within the firm or from high institutions of learning. To ensure its employees in various parts of the word are motivated and are focused at attaining their own goals and those of the organization, General Motors should adopt McClelland's Human

Superfoods Essay Example | Topics and Well Written Essays - 500 words

Superfoods - Essay Example One of the world healthiest food? Yes we are talking about almonds. Almonds definitely are listed as superfood too. These are full of vitamin E, copper, fiber, magnesium and phosphorus. Almonds act as a catalyst to boost up the functioning of brain. It provides double protection against diabetes and their healthy fats are very useful to lose weight also ensuring the lower risk of weight gain. Pistachio nuts are regarded as superfoods as they help you in losing the weigh due to their low cholesterol level and effective fibers. Talking about figures thirty pistachio nuts cause you only 100 calories. Most importantly they are tasty and addictive. Once you start eating pistachio nuts you can barely keep your hands off unless and until all you got on plate is their shells.Talking about superfoods how we can forget carrots? Carrots are the ultimate source of Vitamin A. This beautiful, crunch red vegetable comes with numerous advantages. â€Å"Carrots are good for eyes†, we’ve been listening this statement from our childhood and it is true. Carrots are perfect for good vision as Vitamin A is transported to retina thus providing instant pigmentation for good vision. Also carrots prevent from cancer and reduce the risk of other fatal disease by increasing the immune system. Even some components of carrots are being used to produce anticancer medicines. Carrots are also useful for anti-aging purposes. So all the above mentioned foods are superfoods which intake can ensure you a sound body with sound mind.

BUY LOCAL FROM New Brunswick, Canada INFORMATION TECHNOLOGY FIRMS Research Paper

BUY LOCAL FROM New Brunswick, Canada INFORMATION TECHNOLOGY FIRMS - Research Paper Example By the early 1990s companies identified the problem and thereafter they have been working to solve the difficulties of associated with retaining the talented employees (Mitchell, Holtom, Lee, T, & Graske, 2001). Internal Policies It is also important to note that management and usage of ICT systems are two different fields because the former function lies with the technical staff that has the duty and responsibility of keep the infrastructure up and running. Yet, the second function lies with the managerial staff that should have the ability of extracting and using information from the ICT systems to make effective business decisions. The companies are offering flexible timing, paid leaves, casual dressing and regular increase in the pay for core employees in every department of the organization. The organizations are also known to encourage employees to identify the need of enhancement in the current technology level that will help them in keeping up with the technological level of the industry (Brady, Brookes, & Fellenz, 1986). According to many researchers the technological advancements will define the leaders in the industry. In the light of above argument, it can be established that employees who have the ability to manage ICT systems and those who can use them to make business decisions will define the competitive advantage of the companies in near future (Eriksson, Niitamo, & Kulkki, 2005). Economic Incentives The companies that are currently engaged in the practice of acquiring advanced ICT systems are suggested to offer well to excellent incentives to the staff so that their tendencies to leave the job can be minimized (Doran, et al., 2006). Moreover, it would not be a bad idea to evaluate and analyze the ability of new recruits to understand and comprehend routine technological tasks. Additionally the companies are suggested to buy those ICT systems that are well aligned with the current technological awareness of the employees. The companies should a lso make sure that they do not initiate company-wide technology change more often. It is better to bring system changes within operational level to increase the productivity. The companies should buy those technologies that will help them in driving down the cost because in latest organizational strategy cost control is one of the most important facets. Finally it is necessary for the organizations to hire technology experts as employees because in this form of employment they can resolve the issues more swiftly than in the capacity of consultants. Technology consultants are also notorious for delaying the process of repairs that causes productivity of the entire organization to diminish. External Challenges As mentioned earlier that companies are facing the challenge of retaining employees therefore they have to keep the jobs interesting and on the other hand companies are required to pay excellent wages and salaries to the employees. The intelligent companies always ensure that th ey are paying higher compensations in comparison to the competitors because money and financial well-being is a noted method of growing organizational commitment in the staff. Another modern technique to enhance organizational commitment is to develop a participative model of decision making in the company so that everyone can feel as a part of the organization (Vroom & Jago, 1978). The companies are also anticipated to establish strong personality-

Podcasts Essay Example | Topics and Well Written Essays - 1250 words

Podcasts - Essay Example In this scenario, subscribers are able to listen to podcasts using their computers, rather than sending them to a portable audio player. In fact, it is expected that coming editions of podcasting will include video signal. In this scenario, the cell phones with video potential will be capable of playing video podcasts. Actually, Adam Curry presented the idea of Podcasting. The application of this idea rose extensively with the emergence of networks and radio making material available for podcast fans. According to a research conducted by â€Å"USA Today† in February 2005 stated that over 3,300 podcast applications were available, immediately few months after its opening (Egger; Kayne; Lesinski, Walker and Leveque). Moreover, innovative technology based media has often replaced older media. However, it immediately does not take place that way. In fact, there are various aspects that turn out to be strictly out-of-date and have been replaced because of harsh boundaries they had (smoke signals are not that well-known any longer) however by and large, latest and innovative technology based media immediately supplements older media. Though, gestures did not turn out to be out of date for the reason that of speech. Additionally, the speech did not move away for the reason that of writing. In the same way, books did not put back the trend of letters. In addition, radio did not make books go absent, and neither did TV replace radio. On the other hand, the media backdrop is developing and the various kinds of media are affecting each other. Since people usually like to watch the Super Bowl on TV in place of listening to it on the radio. However, that is not equivalent "replacement". Additionally, radio certainly had to alter when TVs turned out to be well-known, however on the alternately, the number of radio stations almost certainly has augmented in those days (Egger; Kayne; Lesinski, Walker and Leveque). In this scenario, we have