Expansion of the database of MSDRD and analyses of S-N fatigue test data in ultra-long life regime

The Research Group for Statistical Aspects of Material Strength [RGSAMS] has constructed and expanded the Material Strength Database for Reliability Design of Machines and Structures [MSDRD] by newly inputting fatigue data in the ultra-long life regime. When extracting long life fatigue data of metallic materials, duplex S-N characteristics consisting of two components for surface induced fracture and interior defect induced fracture were analyzed using a procedure proposed in this work. The difference between the slopes of S-N curves for the respective components was successfully explained by the difference of "m" in Paris\´ law in a vacuum and room atmosphere