On transient growth of wear pattern properties

A system consisting of a two-degree-of-freedom oscillator with sliding interfaces to two surfaces subjected to wear is investigated with respect to surface evolution and wear pattern dynamics. The system shows the usual possibility of wear pattern generation due to instabilities of the surface evolution equations. As a novel phenomenon in the context of wear pattern dynamics it is shown that, depending on initial conditions, transient growth of surface properties is possible even in the case of linear stability of the surface evolution. An explanation of the effect is given in terms of non-orthogonality of the surface evolution modes. The effect is to be expected in technical applications with multiple surfaces subjected to wear, like, e.g. friction brakes, and could be regarded as an additional mechanism leading to the generation of surface properties due to wear pattern dynamics.