On the Fatigue Damage of 7 : 3 Brass Specimens under Combined Stress

Abstract

Following the previous paper (under reversed bending and torsion), fatigue damage of 7 : 3 brass specimens under combined stress is researched by 'annealing-electropolishing method'. Standard damage life, N₀, is decided under two stress levels respectively. According to the results, fatigue damage concentrates on the surface of the specimen. N₀ becomes shorter rapidly, as σ_n becomes greater, which is normal stress on the plane of maximum shearing stress. If the ratio of number of stress repetitions to N₀ is constant, then the depth of fatigue damage layer is constant also under various stress states. Knowing N₀ under reversed torsion, the depth of fatigue damage is decided using an emprical formula, under various stress states.