含多处损伤未加筋铝合金-壁板的剩余强度

 进行了含多处损伤（MSD）的未加筋LY12CZ铝合金壁板的剩余强度试验。用0.12的钼丝切割预制裂纹，在垂直于裂纹面的方向施加单调增加的拉伸载荷，直至壁板破坏。得到了含不同裂纹几何的未加筋壁板的剩余强度。试验结果表明随着主裂纹长度增加，未加筋壁板的剩余强度减小；对相同的主裂纹长度，主裂纹和相邻的MSD裂纹之间的距离b减小，平板的剩余强度也减小。用5种失效准则分别计算了每个壁板的剩余强度。与试验结果的比较表明，净截面屈服准则和表观断裂韧性准则的误差较大，塑性区连通准则预测的平均误差为22.17%，改进的表观断裂韧性准则的平均误差为16.98%，而改进的塑性区连通准则预测的平均误差为8.27%，改进的塑性区连通准则大大提高了预测结果的精度。

Residual Strength of Unstiffened Aluminum Alloy Panel with Multiple Site Damages

The residual strength tests of unstiffened aluminum alloy LY12CZ panels with multiple site damages(MSD) were carried out.The lead crack and the small cracks at rivet holes were simulated by saw cuts.Each specimen was subjected to a monotonically increasing tensile load perpendicular to the crack surface until failure occurred.The residual strengths of these panels with different crack sizes were obtained.The experimental results showed that the residual strengths of the panels would decrease as the lead crack length increased and for the same lead crack size,the residual strengths of the panels would decrease as the distance b between the lead crack tip and the adjacent MSD crack tips reduced.The residual strengths of the panels with multiple site damage were evaluated by five different failure criteria respectively.Compared with the experimental results,it is shown that for panels with different lead crack sizes and different b values,the average error for net section yield criterion and K-apparent criterion was too great,while the average error for plastic zone link up criterion and improved K-apparent criterion were 22.17% and 16.98% respectively,and that for improved plastic zone link up criterion was 8.27%,suggesting a notable improvement in prediction with the improved model.