Wave-Form Effect on Fatigue Strength and Its Rheological Analysis

Abstract

The stress wave under service is generally non-sinusoidal. The fatigue test by non-sinusoidal loading was made and compared with the sinusoidal stress wave fatigue test. Wave forms selected are 5 c/sec sinusoidal, square and triangular and 11.5 c/sec sinusoidal. The test results show that, for test specimens of 0.3% carbon steel, especially for unnotched specimens, the fatigue strength differs significantly with different wave patterns, for the reason mainly of different amounts of repeating plastic strain. Then, an attempt was made to obtain an analytical expression of wave-form effect in terms of the relationship between stress and plastic strain during the fatigue test using a rheological model.