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• File released: /SLFFEA/1.5/slfmesh15.tgz

  posted 311 days ago

• File released: /SLFFEA/1.5/slffea15.tgz

  posted 311 days ago

• SLFFEA 1.5 file released: slfmesh15.tgz

  Science Code Changes * Expanded the double curved shell to handle triangle elements. The 4 node shell element can now handle 3 nodes. One problem though is the execssive stiffness I encountered with other triangle elements. The 3 node version should therefore be used only to get qualatative results. The data for a 3 node element is essentially the same as a 4 node element except that the element connectivity listing 3 nodes. * Added several non-linear(large deformation) codes and cleaned up the brick and truss non-linear codes. So now it is possible to use the conjugate gradient method as well as dynamic relaxation. The following elements now have non-linear counterparts. 1. brick element 2. quad element 3. tetrahedron element 4. triangle element 5. truss element 6. wedge element As with most non-linear FEA software, these calculations require a little art in the selection of parameters which will keep the program stable as it iterates toward the solution. Determination of when convergence is reached as well as the choice of time step and damping so that the calculation is stable are considerations for which users will have to carefully decide. * I have changed the format of the non-linear input file files so that the parameters are better labeled as well as some additional features. The input file looks like: dynamic relaxation(DR) or conjugate gradient(CG) method ( 0 = CG, 1 = DR ) 1 number of iterations for DR or CG 20000 time step for DR 1.0 damping constant for DR .02088 stress calculation for CG (Lagrangian = 0, stress updating = 1) 1 Most of the above should be clear, except for the "stress calculation for CG" which tells whether the stress should be calculated based on "stress updating" or whether calculated at the end using the final displacements. I compared the results for both with dynamic relaxation which only uses stress updating and neither method matched more than another. Graphics Code Changes # The graphics codes for the shell has been modified to display the 3 node elements. I have also added a few new mesh gererators which will also be included in SLFMESH-1.5. They generate meshes for a brick hose element and wedge loop and spring elements.

  posted 312 days ago

• SLFFEA 1.5 file released: slffea15.tgz

  Science Code Changes * Expanded the double curved shell to handle triangle elements. The 4 node shell element can now handle 3 nodes. One problem though is the execssive stiffness I encountered with other triangle elements. The 3 node version should therefore be used only to get qualatative results. The data for a 3 node element is essentially the same as a 4 node element except that the element connectivity listing 3 nodes. * Added several non-linear(large deformation) codes and cleaned up the brick and truss non-linear codes. So now it is possible to use the conjugate gradient method as well as dynamic relaxation. The following elements now have non-linear counterparts. 1. brick element 2. quad element 3. tetrahedron element 4. triangle element 5. truss element 6. wedge element As with most non-linear FEA software, these calculations require a little art in the selection of parameters which will keep the program stable as it iterates toward the solution. Determination of when convergence is reached as well as the choice of time step and damping so that the calculation is stable are considerations for which users will have to carefully decide. * I have changed the format of the non-linear input file files so that the parameters are better labeled as well as some additional features. The input file looks like: dynamic relaxation(DR) or conjugate gradient(CG) method ( 0 = CG, 1 = DR ) 1 number of iterations for DR or CG 20000 time step for DR 1.0 damping constant for DR .02088 stress calculation for CG (Lagrangian = 0, stress updating = 1) 1 Most of the above should be clear, except for the "stress calculation for CG" which tells whether the stress should be calculated based on "stress updating" or whether calculated at the end using the final displacements. I compared the results for both with dynamic relaxation which only uses stress updating and neither method matched more than another. Graphics Code Changes # The graphics codes for the shell has been modified to display the 3 node elements. I have also added a few new mesh gererators which will also be included in SLFMESH-1.5. They generate meshes for a brick hose element and wedge loop and spring elements.

  posted 312 days ago

• File released: /SLFFEA/1.4/slffea14.tgz

  posted 816 days ago

• SLFFEA 1.4 file released: slffea14.tgz

  Science Code Changes * Expanded the quad and triangle elements. 1. The 4 node quadrilateral element can now handle 3-D membrane problems in addition to the plane strain/stress problems. 2. The 3 node triangle can now handle 3-D membrane problems in addition to the plane strain/stress problems. * The plate element is now also a 3-D element with membrane properties in addition to bending. Other changes include: 1. It also can handle 3 node plate meshes. 2. It has new stress and strain states xx, yy, zz and principal stresses and strains I, II, III. 3. From the membrane, there are also x and y displacements as well as rotations in z. * The shell element has had some significant changes. 1. Principal stresses and strains have been completely redone so that stress and strain zx and yz are part of the principal stress/strain calculation. This means that I have gone from having only a 2-D principal stress/strain state to a 3-D stress/strain state. I omitted this before because there is no stress/strain zz, but the stress/strain zx and yz should not have been ignored in the calculation of the principal stresses and strains. I have propagated this fix to all the older codes. 2. Changed the name of Uz_lam to Uz_fib because this is really the displacement prjected in the e3 fiber direction rather than the e3 lamina direction. I have propagated this change to all the older codes because it is more accurate. 3. Fixed a bug relating to the updated coordinates for modal analysis problems. In my calculation for the updated coordinates, the quantity Uz_fib(formerly called Uz_lam) wasn't being calculated for modal analysis problems. I have added the necessary code to all the older codes in addition to the current one. 4. The way the deformed coordinates are calculated based on the undeformed coordinates has changed so that it is slightly more correct. You can read about it in the code "shwriter.c" for when I write out the coordinates of the output file. I don't think this causes very significant changes, so I am not making this change for the older codes. Graphics Code Changes 1. The graphics codes for the plate, quadrilateral, and triangle have been modified to display the expanded capability of the elements. This is the most significant for the plate which now has many more stress and strain states. 2. The shell element has small modifications based on the new way updated coordinates are calculated. I have also consolidated a lot of the redundant science and graphics codes into source files that are common to multiple elements. This has eliminated a significant amount of code. Of course, the expansion of the plate, quad, and triangle elements has added much more code.

  posted 816 days ago

• SLFFEA 1.0 file released: slffea.tar.Z

  posted 817 days ago

• File released: /SLFFEA/1.0/slffea.tar.Z

  posted 817 days ago

• File released: /SLFFEA/1.0/slffea.tgz

  posted 817 days ago

• File released: /SLFFEA/1.1/slffea11.tgz

  posted 817 days ago