Applying a population growth model to simulate wear of rough surfaces during running-in

A population growth model (PGM) is introduced to simulate wear during running-in, which is one of three typical wear states. The rough contact region is divided into several bar-shaped elements while the wear of every grid point has been considered as a PGM process. The wear volume in rough surface can be calculated during the wear processes and the proposed wear formula contains three items: initial point height, determine function and stochastic function. By employing a PGM, the changes of every local peak and valley were simulated. The results show that the height of local peak dynamically decreased and the decreasing speed becomes slow during running-in, whereas, the local valley shows inverse tendency. Because the stochastic function contains Brownian motion, if a point is higher than other points at time t, it may be lower than other points at time t+δt. Furthermore, if the height of every discrete point conforms to a PGM, the expectation of the wear volume follows an exponential form.