Influence of stress gradients on failure in contact strength tests with cylinder loading

Bars loaded by opposite concentrated forces via rollers are appropriate test specimens for the determination of strength under contact loading. The contact strengths measured revealed strongly reduced Weibull exponents compared with those from four-point bending tests. This was the reason for a study of the strong stress gradients in contact strength tests. It can be shown that the strongly non-homogeneous stresses lead to a reduced Weibull exponent.