Chapter 10 - Contact problems: Failure processes at points of contact between bodies

Abstract

This chapter focuses on the stresses that arise due to local contact between bodies. Such contact can give rise to stresses which are very high and highly localized, creating significant stress gradients. Many industrial components rely on such contacts, for e.g. bearings and joints, not only in machine components but also in the joints of the human body and their replacement parts. Many mechanical devices would be impossible without contact between parts, and yet it is particularly difficult to predict the failures which occur at these locations. The basic stress analysis of contact situations is quite problematic, being strongly affected by factors which are difficult to estimate, such as the degree of friction and adhesion between moving bodies. Cracking is a common feature of contact-related failures, suggesting the use of fracture mechanics in their solution. Short cracks and non-propagating cracks are frequently involved as a result of crack growth through a rapidly decaying stress field. Therefore, methods such as the theory of critical distances (TCD) may be applicable. This chapter also reviews the existing methods used to predict failure under monotonic and cyclic contact, with particular emphasis on the problem of fretting fatigue.