Experimental analysis on friction increment of surface textured flexible couples

Abstract

The apparent friction force of spherical convex textured rigid bodies sliding on soft materials was tested and analyzed in order to develop the technology of friction increment for frictional transmission. The rigid bodies were made of Polylactic Acid (PLA) by 3D printing, and the counterparts were made of Ethylene Propylene Diene Monomer (EPDM). Experimental results show that the spherical convex surface texture increased the friction coefficient effectively compared to that of non-textured couples. The parameters include the radius of the texture, the hardness of the soft material and the normal load play important roles in the friction increment. The mechanism of the friction increment was analyzed. The apparent friction force consists of sliding friction force and ploughing force. The ploughing force which induced by the embedment of the spherical convex texture in the soft material depends on the normal force and therefore has influence on the equivalent friction coefficient. The effective angle and embedment number were proposed to model the contact state of the friction couples. The nonlinear dependence of the embedment number on the parameters of spherical convex textures and the properties of the soft materials was analyzed. The summarized model based on the experimental result can be used to predict the equivalent friction coefficient.