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用弹塑性有限元方法,以裂尖张开角参数为断裂准则分析了双轴载荷比对含裂纹加劲曲板中扩展裂纹尖端应力场、塑性区形状和尺寸,加劲桁条中应力分布及加劲曲板结构剩余强度的影响。发现双轴载荷比的增大使曲板的曲率增大,明显改变了扩展裂尖处应力分布、塑性区的形状和尺寸,虽可提高起裂名义应力,但却使整个结构的剩余强度明显降低。加劲曲板结构的最终破坏是因蒙皮中裂纹快速失稳扩展所致,而这种失稳扩展是由加劲曲板内侧裂尖局部处材料的塑性垮损开始的。
The elastic-plastic finite element method is used to analyze the crack tip stress field, the shape and size of the plastic zone, the stress distribution in the stiffening stringer and the stiffened plate in the cracked stiffened plate by using the crack tip open angle parameter as the fracture criterion. Effect of structure residual strength. It is found that the increase of the biaxial load ratio increases the curvature of the curved plate and obviously changes the stress distribution at the crack tip and the shape and size of the plastic zone. Although the nominal stress of the initiation of cracking can be increased, the residual strength of the entire structure is significantly reduced . The ultimate failure of the stiffened plate structure is due to the rapid and steady propagation of the crack in the skin, which begins with the plastic collapse of the material at the crack tip inside the stiffened plate.