Real contact area, contact temperature rise and transfer film formation between original and worn surfaces of CF/PEEK composites sliding against steel

For composite-steel surfaces in sliding contact an anisotropic numerical contact algorithm [7] has further been developed to study the "layer type" problems and FE contact analysis was applied to evaluate the contact parameters (real contact area, contact pressure distribution and normal approach). The contact temperature rise was evaluated by using a numerical thermal algorithm for stationary and a FE transient thermal technique for "fast sliding" problems. The effect of a continuous transfer film layer (TFL), that had built-up during wear of the PEEK matrix material on the steel counterpart, was considered. Its thickness was assumed to be t=1 mu m, and its material properties were that of PEEK at room temperature or, in the case of frictional heating, at a temperature of 150 degrees C (i.e. above the glass transition temperature of the polymer matrix). Results are presented for real composite-steel surfaces (eased on measured surface roughness data) in sliding contact. The TFL has effect on the contact parameters especially at the higher operating temperature assumed (i.e. 150 degrees C), by producing a larger real contact area and a lower contact pressure distribution. The contact temperature rise is clearly higher if a TFL is present. Due to the low thermal conductivity of PEEK, TFL is near to the melting state or molten at the small vicinities of the contact spots of the real contact area.