An assumed enhanced displacement gradient ring-element for finite deformation axisymmetric and torsional problems

When analyzing axisymmetric solids under torsion the possible reduction of the problem by one dimension, say the independence of the displacement- and rotation- eld of the cylindrical (angle) co-ordinate , should always be exploited. Whereas in the geometrically linear range the purely torsional problem, described by the rotational angle only, is always decoupled from the purely axisymmetric problem,1 described by the radial and axial displacements u and v only, this is not the case in nite deformation torsional problems. Thus, the nite deformation axisymmetric nite element with ve enhanced gradient parameters2 can easily be extended to a nite deformation axisymmetric and torsional nite element with seven enhanced gradient parameters. Numerical results of two classical benchmarks, the in-plane torsion test3 and the necking of a circular bar,5; 4; 2 are presented