Numerical simulations of mild wear using updated geometry with different step size approaches

Wear of engineering components is often a critical factor influencing the product life. Prediction and simulation of wear is therefore an important matter in engineering. Numerical simulations of wear of a cylindrical steel roller oscillating against a steel plate are performed with a special version of the finite element program NIKE2D. The simulation was done in steps and the pressure and the sliding distance was recalculated as the surface geometry changed. The wear model used in the simulations is global. The global wear model gives an opportunity to predict the change in shape of the surfaces in a fast and efficient manner. it will however not incorporate information on how the wear occurs on molecular scale. Two different strategies in selecting the time step for the geometry update were used. In the first case a larger time step was used in the first wear steps and a smaller one in the final ones, and in the second a constant time step was used. To get information on the coefficient of friction an experiment was performed. This experiment was used to evaluate the simulation as well as give the proper input to the simulation. The simulated topography of the surfaces was compared with experimental results and the agreement was good. It can be concluded that allowing the time step to differ between the wear steps will speed up the wear simulation considerably. A large time step for the geometry update will cause some waviness of the cylindrical surface but when the smaller time steps have been used at the end of the computation this error will disappear. (C) 2001 Elsevier Science B.V. All rights reserved.