Abstract: The concept of weight-averaged maximum shear strain plane is proposed on basis of analyzing characteristics of shear strain on material planes. A procedure is presented to determine the fraction plane under multiaxial random loading. The angle values of the planes that experience peak values of maximum shear strains are averaged by employing the weight function, which is assumed to take into account the main factors of influencing the fatigue behavior, e.g. fatigue damage. The proposed algorithm is applied to the multiaxial in- and out-of-phase experiments to assess the correlation between the weight-averaged maximum shear strain direction and the position of the experimental fatigue crack initiation plane.

Key words: Critical plane approach, damage, Fatigue, Fatigue fracture plane, Maximum shear strain plane, Multiaxial random loading, Weight-averaged method, Frequency feature, Healthy state, Modulation sidebands, Steady-type fault, Gear system