Rolling fatigue crack growth test method and rolling fatigue life prediction method

摘要

PROBLEM TO BE SOLVED: To provide a testing method that makes it possible to observe fatigue crack, which has conventionally been impossible, by a roll fatigue test, and makes it possible to quantitatively evaluate the progress characteristics of roll fatigue crack, and to provide a roll fatigue life estimation method that enables fatigue life design for a roll bearing based on the view of fracture mechanics.SOLUTION: A roll fatigue test is conducted in such a manner that a roll body is placed on a test piece with a minute hole made therein, and the roll body is rolled on a roll-body path that passes on the minute hole, thereby repeatedly applying stress on the test piece. Thus a crack starting from the minute hole is caused. After the roll fatigue test is conducted a plurality number of times, the test is stopped. The length of a crack caused in the test piece is measured every time the test is stopped, and a roll fatigue crack progress curve indicating the relation between the number of times that stress application is repeated and the crack length is obtained. Using the maximum amplitude of shear stress caused in a material when a roll bearing is used, and using the dimension of the maximum inclusion of the stress volume of the roll bearing, the roll fatigue life of the roll bearing is estimated based on a roll fatigue crack progress speed graph.