The CONTACT software created by Kalker and further developed by Vollebregt has recently been integrated in dynamical simulation software like RecurDyn and libraries usable in Matlab or C. When such larger packages impose small timesteps compared to the gridsize used, a wiggle-like phenomenon arises. Additionally, transient time-stepping appears to give rise to a smoothing effect that alters detailed traction profiles. A method is presented that focuses on scaling of the timestep for the influence coefficient matrices. This method stops the occurrence of wiggles. Furthermore, the smoothing effect is explained and a solution for this problem is proposed using world-fixed coordinates. These two refinements result in an improved algorithm that allows for small timesteps to be chosen in CONTACT, producing results consistent with results using larger timestep sizes. ... Read more

The boundary element method (BEM) is widely used in fast numerical solvers for concentrated elastic contact problems arising from the wheel-rail contact in the railway industry. In this paper we extend the range of applicability of BEM by computing the influence coefficients (ICs) numerically. These ICs represent the Green's function of the problem, i.e. the surface deformation due to unit loads. They are not analytically available when the half-space is invalid, for instance in conformal contact. An elastic model is proposed to compute these ICs numerically, by the finite element method (FEM). We present a detailed investigation to find proper strategies of FEM meshing and element types, considering accuracy and computational cost. Moreover, the effects of computed ICs to contact solutions are examined for a Cattaneo shift contact problem. The work in this paper provides a guidance to study fast solvers for the conformal contact. ... Read more