Some Benchmark Problems for FEA from Torsional Behavior of Rubber

Two commercial finite element analysis (FEA) programs, ANSYS and FLEXPAC, were compared in benchmark problems involving torsion of cylindrical rubber specimens. The effects of using different element types, material models, bulk moduli and specimen geometry were studied and compared with Rivlin's theoretical solution. This was done as an exercise to help build confidence in the analyst's ability to use these codes properly and in the reliability of the results. Some problems with certain element types were identified. With suitable choices, FEA results consistent with the theoretical solution were obtained.