ACOUSTIC EMISSION CHARACTERISTICS OF SURFACE FRICTION IN BIO-MEDICAL APPLICATION

摘要

The paper describes the use of acoustic emission (AE) techniques in a study of surface friction properties. All dynamic friction processes generate quasi-continuous AE signal, which can be used to characterize surface friction. The AE signal is produced by stick-slip motion of two materials in contact. Signal intensity depends on contact force, motion velocity, molecular adhesion forces between both materials, and surface properties as roughness, hardness, elastic and plastic properties and surface layer properties (lubrication, dry friction). A series of tests have been performed using a new prototype of friction brush probe combined with tangential force measurement. This probe has been designed for measurement of human skin friction coefficient, but can be applied also to other materials. Measured signals (AE signal, tangential and normal forces) were recorded and analyzed by digital processing analyzer DAKEL-XEDO. Various friction head materials were tested on samples made of different materials. The best results were obtained using carbon-fiber brush friction head. The contact force and motion velocity were optimized to produce maximal AE signal amplitude at a contact force as low as possible. Good correlation was observed between frictional forces and global AE activity parameters.