A MULTIAXIAL FATIGUE DAMAGE MODEL FOR ORTHOTROPIC MATERIALS UNDER PROPORTIONAL LOADING

A new multiaxial fatigue damage model for orthotropic materials is pro posed based on the strain vector. Six material constants are included in the model. These material constants represent the dependence of fat igue resistance on material orientation, and they can be obtained by c onducting strain-controlled uniaxial fatigue tests along the three pri ncipal orthotropic directions of an orthotropic material. The model ca n also be transformed in new coordinate systems to predict the fatigue lives of new material orientations. Biaxial low-cycle fatigue tests a re conducted to verify the model. The prediction of the model agrees w ith the experimental results reasonably well.