ABSTRACT
Loads acting between the rolling elements and raceways in rolling bearings develop only small
areas of contact between the mating members. Consequently, although the elemental loading
may only be moderate, stresses induced on the surfaces of the rolling elements and raceways
are usually large. It is not uncommon for rolling bearings to operate continuously with
normal stresses exceeding 1,380 N/mm2 (200,000 psi) compression on the rolling surfaces.
In some applications and during endurance testing, normal stresses on rolling surfaces may
exceed 3,449 N/mm2 (500,000 psi) compression. As the effective area over which a load is
supported rapidly increases with the depth below a rolling surface, the high compressive stress
occurring at the surface does not permeate the entire rolling member. Therefore, bulk failure
of rolling members is generally not a significant factor in rolling bearing design; however,
destruction of the rolling surfaces is. This chapter is therefore concerned only with the
determination of surface stresses and stresses occurring near the surface. Contact deform-
ations are caused by contact stresses. Because of the rigid nature of the rolling members, these
deformations are generally of a low order of magnitude, for example 0.025 mm (0.001 in.) or
less in steel bearings. It is the purpose of this chapter to develop relationships permitting the
determination of contact stresses and deformations in rolling bearings.
