Service life and fracture of solid bodies under the conditions of cyclic contact interaction

Abstract

A numerical-analytic model is formulated for the investigation of fracture processes and evaluation of the residual service life of solid bodies under the conditions of cyclic contact interaction. The model is based on the criteria of fracture of materials in the process of growth of fatigue cracks and the algorithms of step-by-step construction of the paths crack propagation developed by the method of singular integral equations for two-dimensional contact problems of the theory of elasticity for bodies with curvilinear cracks. The model is realized for contact interactions of rolling and fretting fatigue. The causes and specific features of the formation of typical defects in rolling bodies of revolution, such as pitting, spalling, squat defects, and cracking are analyzed depending on the operating parameters of a rolling couple. It is shown that, both in the case of rolling and under the conditions of fretting fatigue, the character of fracture of the contact surface and the sizes of debris particles are strongly affected by the value of the friction coefficient, the distribution of tangential forces between contacting bodies, the characteristics of cyclic crack-growth resistance of the material, and the service or random products in the contact zone (water, lubricants, powder fretting products, etc.). We present examples of evaluation of the residual service life of rail (RSB12) and roller (9KhF and GH) steels.