MODIFIED MCDOWELL MODELAND RATCHETING PREDICTIONS OF 1070 STEEL

McDowell model is employed to predict ratcheting of 1070 steel under proportional and nonproportional loading paths. An evolutional function of uniaxial parameter A_i related to plastic strain accumulation is introduced into McDowell model. It is shown that the modified McDowell model can present accurate predictions of ratcheting effect under uniaxial cyclic loading with mean tensile and compressive stress. The model also works well for tension-torsional proportional cyclic loading with mean stress, cyclic shear loading with constant axial stress, non-proportional cyclic loading, and multiple step loading with varying axial mean stress. The improved model can also predict well the ratcheting for large number of cycles for these loading cases.