Contact fatigue and tensile stresses

摘要

This work aims at a deeper understanding of spalling type contact fatigue.It is proposed that surface carcks develop due to surface asperities.Then,the nominal stress field (2D) is locally disturbed by asperity contacts (3D) which give tensile stresses.Crack paths in a fractographic study were found to follow the tensile stress hypothesis.A new method is presented: Standing Contact Fatigue (SCF).During SCF testing,contact fatigue cracks were formed in case-hardened steel (with significant residual compressive stresses).Lubrication was not needed for contact cracking to occur.