The Influence of Multiscale Roughness on the Real Contact Area and Contact Resistance between Real Reference Surfaces

When rough surfaces are brought into contact under typical loads, only the peaks or asperities come into contact. The contacts between these asperities govern the friction and wear, and also constrict the conduction of electricity and heat. The asperities exist on many different magnitudes of scales and can also vary in shape. This work uses a stacked multiscale contact model to analyze the structure of typical engineering surfaces. Standard reference surfaces are characterized and used in model. The results show that the multiscale roughness of surfaces, as described by the aspect ratio of each scale, can greatly influence the real contact area, pressure and contact resistance by several orders of magnitude in both the elastic and elastic-plastic regimes. This demonstrates that certain types of machining processes maybe better suited to contact applications.