Characterization of elastic-plastic contact between wavy surfaces formed by different machining methods

Various processing methods exert influence on surface contact behaviors, encompassing aspects of surface periodicity, randomness, and yield stress. This study systematically investigates the contact behavior of surface asperities generated through milling, wire electrical discharge machining (WEDM), and knurling under diverse loading conditions, employing a combination of experimental and numerical approaches. The application of a segmentation-aided digital image correlation (SA-DIC) technique, coupled with a displacement-based elastic-plastic judgment method, allows for direct observation of the elastic-plastic boundary. Further analysis involves Fourier transformation of surfaces produced via distinct processing methods, yielding frequencies of different orders. A comparative evaluation between contact behavior of surfaces generated by different orders of Fourier frequencies and the original surface is conducted. Parameters including contact area, mean contact pressure, and plastic evolution throughout the contact process are comprehensively discussed. Additionally, the impact of surface noise on contact behavior under varying loading conditions is scrutinized. To offer an intuitive portrayal of plastic evolution behavior, this study presents plastic evolution formulas based on mean contact pressure and corresponding interference associated with surfaces formed by each processing method. Furthermore, the study delves into the influence of tangential load and yield stress on plastic evolution. The insights garnered from this research significantly contribute to the analysis of factors influencing contact behavior induced by diverse processing methods.