| An incremental fatigue damage model is developed. The model incorporates the critical plane concept in multiaxial fatigue and the material memory in cyclic plasticity. With an incremental form, the model does not require a cycle counting method for variable amplitude loading. The new approach can explain the experimentally observed phenomena in multiaxial fatigue including the dependence of crack orientation on fatigue life. The constants in the new model can be determined from uniaxial and pure torsion test results. Experimental results of several materials are used to verify the new model. The experimental data include 1045 steel under block loading, 1070 steel and 304 stainless steel under proportional and nonproportional loading, 304 stainless steel under uniaxial step loading, EN15R steel under multiaxial variable amplitude loading, and 1070 steel under uniaxial ratchetting loading. The results indicate that the new fatigue damage model can satisfactorily correlate the experimental results for a wide range of materials and loading conditions. |
