Abstract: Contact stiffness is one of the most important parameter in the characteristics of joint surface, which directly affects the dynamic characteristics of the whole mechanical structure. GW (Greenwood & Williamson) model is a widely accepted contact model and has obtained good agreement with many experiments. Theoretically, the prediction results of GW model are affected by instrument resolution, consequently are not unique,but macroscopic physical parameters such as stiffness and conductivity are unique values. This contradiction implies that there is a single computational or observational scale to ensure the uniqueness of macroscopic results. The scale-dependent characteristics of GW model are analyzed theoretically. The method to change the computing scale by Gaussian filter is researched. Based on Thomas' contact theory, an iterative method is designed to determine the cutoff frequency of the filter, and a stiffness calculation framework for the joint surface taking scale into consideration is ultimately proposed. A tangential stiffness test-bed is built to verify the model considering scale. The results show that the model considering scale can better consist with the experimental results.

Key words: real contact area, contact model, scale dependence, GW model, MB model