Effect of Mean Stress on Fatigue Srength, Crack Strength and Notch Radius at Branch Point in Axial Fatigue of 7:3 Brass

概要

論文の詳細を見る
The rotating bending and axial fatigue tests of plain and notched 7 : 3 brass specimens were carried out.The main results obtained are as follows.(1) The characteristic in fatigue of notched specimens under rotating bending stress is similar to the one under completely reversed axial stress, and the root radii of notches at the branch point ρ_0 (branch point means the critical point for a non-propagating crack to develop) are about 0.6 mm for both cases.(2) The relations of σ_<w1>/σ_<w0> and σ_<w2>/σ_<w0> (σ_<w1> : limit stress for crack initiation, σ_<w2> : limit stress for complete fracture in the range of non-propagating crack existing, σ_<w0> : σ_<w1> of plain specimens) to stress concentraiton factors α are almost the same in rotating bending fatigue of 7 : 3 brass and 0.13 % C steel.(3) In axial fatigue, the maximum stress repeated at a notch root at the crack initiation limit ασ_<w1> becomes almost constant irrespective of mean stress, if the stress gradient χ is constant.(4) In axial fatigue, ρ_0 increases as mean stress decreases. This means that σ_<w2> increases as mean stress decreases.