用柔度法和数值法确定疲劳裂纹的闭合效应

DETERMINATION OF FATIGUE CRACK CLOSURE EFFECT BY COMPLIANCE TECHNIQUE AND NUMERICAL METHOD

用柔度法中的裂尖应变法测定了车轴钢缺口裂纹的张开载荷。根据车轴钢的循环应力应变曲线,利用ADINA非线性有限元程序分析了裂尖附近的应力应变场。计算了缺口裂纹的张开载荷。柔度法和数值法的结果吻合。本文提出敏感点的概念,实测张开载荷的关键在于将应变片布置在敏感点上。实测和有限元计算证实敏感点是裂尖前方应变线性最佳而应变值又较大的位置。

The open load of notch crack of the axle steel was determined by the method of crack-tip strain gauge in compliance technique, and on the basis of the cyclic stress-strain plot, calculated by the analysis of the stress-strain field ahead of crack-tip with aid of the ADINA non-linear finite element program as well. Both results are identical. A proposal of sensitive point, on which a strain gauge was already attached, was made as the key to determine open load. The measured and calculated results certified that the sensitive point is the position of best linear and more great strain ahead of crack tip.