Contact Fatigue in Hard Steel Specimens with Point and line Contacts

Abstract

Kennedy and others have repeatedly loaded steel spheres together and produced ring cracks due to the radial tensile stress that exists at the edge of the contact zone. Merritt has pointed out that no such tensile stress exists in line contact. Tests similar to those of Kennedy have now been carried out both in line and point contacts. Both produced cracks. The cracks in line contact have been explained by residual tensile strains which develop near the edges of the contact zone when the elastic limit has been exceeded.A number of interesting features which appeared in the tests both with line and point contacts are noted.