摘要
不锈钢材料在复合加载条件下（Ⅰ＋Ⅱ），裂纹的扩展有两种典型，即发生拐弯或分支扩展。通常当双向载荷为同向时，裂纹只改变扩展方向（拐弯），且随着二载荷比λ（＝Ｐｙ／Ｐｘ）从０→１时，转向角β从４５°→０°。当双向载荷为反向时，λ从０→－１，裂纹只发生分支，且分支夹角始终为一定值，二分支在扩展中逐渐平行于二载荷轴。对裂纹尖端的应力强度因子ＫⅠ和ＫⅡ的计算表明，复合加载下裂纹通过拐弯或分支，使ΔＫⅡ→０。拐弯或分支后的裂纹扩展速率可以用ＫⅠ描述。
Two kinds of fatigue crack growth appear in stainless steel under Mixed Mode loading, i.e. the crack deflected or branched. In general, when the biaxial loads are in phase, deflected cracks are obtained. The deflected angle β decreases from 45°→0°,with increasing λ (0→1). When the biaxial loads are out phase, branched cracks are obtained only. But the branched angle β for -1≤ λ <0 does not seem to be related to λ . The crack paths which follow in the wake of fatigue crack growth become parallel to the loading axis. The calculated stress intensity factors show that along the deflected or branched crack path, Δ K Ⅱ is almost zero, and Δ ? ? Ⅰincreases with crack growth so that the deflected or branched fatigue cracks all propagate in Mode Ⅰ. These results are useful when applied to practical structural components.
出处
《南京化工大学学报》
1997年第1期18-23,共6页
Journal of Nanjing University of Chemical Technology(Natural Science Edition)
关键词
裂纹扩展
载荷比
疲劳
不锈钢
fatigue crack growth\ branching\ deflecting\ loads ration
