INFLUENCE OF THE HARDENING BEHAVIOUR IN THE ELASTIC-PLASTIC CONTACT

Elastic-plastic contact problems lack analytical solutions due to mathematical complexities associated with both elastic contact processes and the theory of plasticity. Prediction and understanding of the mechanisms that lead to contact failure under heavy load thus rely on numerical methods, with finite element method as a strong candidate due to its strong applicability. However, the latter comes with the price of prohibitive computational burdens when highly localized gradients are found. Special numerical methods have been developed in the literature, involving the meshing of only a limited region around the initial point of contact, coupled with the half-space theory. These methods were firstly applied to solve elastic contact problems, but were subsequently extended to more complex materials behaviours such as elastic-plastic or viscoelastic. The fine-tuning of different parts of the algorithm for the elastic-plastic contact has been a subject of interest for many research efforts, aiming to improve its generality and/or its computational efficiency. An important breakthrough was achieved with the integration of numerical techniques usually employed in digital signal processing for the optimal calculation of convolution products. The goal of this paper is to predict by numerical simulation the role of the type of hardening of the elastic-plastic body in the evolution of the contact process. To this end, a previously developed computer code was extended and modified to incorporate kinematic hardening alongside the generally assumed isotropic hardening. Numerical simulations are performed, involving the repeated vertical loading and the repeated rolling of a rigid sphere over an elastic-plastic half-space. It is found that, in the first contact scenario, changing from isotropic to kinematic hardening makes little to no difference, whereas in the second case, a deeper residual print is predicted. Moreover, the residual print grows with each new passing. This process can be attributed to volumes inside the elastic-plastic body subjected to stresses of equal absolute value but of opposite signs. Considering that the predictions of the conducted numerical simulations are aligned with the general theoretical framework, the results reported in this paper are expected to promote an improved comprehension of the elastic-plastic contact processes.