Fatigue criterial parameters of variable amplitude stress

Abstract

In this paper new fatigue criterial parameters of variable amplitude stress are presented. To obtain them it is assumed that the energy expenditure in the fatigue process is proportional to the elastic strain energy. If the increment of damage which is caused by n stress cycles of constant amplitude, a, is related to the elastic strain energy transferred' to unit volume in N cycles which cause failure at the stress amplitude a, then the Palmgren-Miner rule is obtained. If, however, this increment is related to the elastic strain energy transferred to unit volume in n cycles which cause failure at the sufficiently high stress amplitude, A , another formula for the total fatigue damage and additional criterial parameters are obtained.