Abstract: Many experimental data have demonstrated that the fatigue life under non-proportional loading, under the same equivalent strain, is far less than that under proportional loading. Therefore, based on the critical plane, a new multiaxial fatigue life prediction model as shear form based on the strain path is proposed. The maximum damage plane is defined as the critical plane and this model consists of four main damage parameters：normal and shear strain amplitudes on the critical plane, mean hydrostatic strain and a path-dependent factor. The path-dependent factor is presented to consider the influence of non-proportional loading. Meanwhile, the effect of the mean strain is corrected by the mean hydrostatic strain. It does not include any material constant which is very convenient for engineering design. Four kinds of materials are used to demonstrate the accuracy of the presented model.

Key words: critical plane method;multiaxial fatigue;life prediction model;path-dependent factor;mean hydrostatic strain