Effect of Strain Hardening on Unloading of a Deformable Sphere Loaded against a Rigid Flat – A Finite Element Study

The present study considers an elastic-plastic contact analysis during loading-unloading of a deformable sphere with a rigid flat using finite element method. The effect of strain hardening on the contact behavior of a nonadhesive frictionless elastic-plastic contact is analyzed using commercial finite element software ANSYS. To study the strain hardening effect different values of tangent modulus are considered by varying the hardening parameter. The range of hardening parameter is chosen in such a way that most of the practical materials belong in this range. The effect of strain hardening is explained through the results of simulations and compared with elastic perfectly plastic models as well as available loadingunloading models. Analysis has been carried out for deformations up to 200 times the critical interference. It is found that the contact parameters during loadingunloading are not of uniform nature within the range of hardening parameters used in this study. Increased strain hardening results in less residual strain and offer less resistance to full recovery of the original spherical shape. Multiple loading-unloading is also done for two extreme cases of hardening parameters to study the fluctuation of dimensionless interference during subsequent cycles. The contact parameters are found identical with first cycle of loading-unloading.