偏心裂纹缺陷板的应力强度因子和极限拉伸强度分析

疲劳裂纹对船舶结构强度具有不可忽视的削弱作用,在过去的研究中,主要从断裂力学的角度对疲劳裂纹应力场进行分析,而对于静态裂纹板的极限强度的探讨相对较少.本文在有限元计算的基础上对具有偏心裂纹缺陷的矩形板的应力强度因子和极限拉伸强度进行了分析.对于偏心裂纹应力强度因子,在计算方法上有效地简化了文献5]中提出的大单元有限元计算模型,并且用于分析裂纹偏心度对于应力强度因子的影响.对于偏心裂纹延性板,采用弹塑性有限元进行了大量的组合计算,分析了相对裂纹长度、材料屈强比和裂纹偏心度对板的拉伸极限强度的影响,并给出了方便计算的回归公式.该回归公式包含了多个参数对板的极限拉伸强度的影响,与实验结果吻合较好.

Stress Intensity Factor and Ultimate Tensile Strength Analysis of Eccentrically Cracked Plates

The effect of the crack eccentricity ratio on the stress intensity fact or and the ultimate tensile strength for cracked ductile plates was investigated in this paper.The analysis is based on the finite element method.In regard of t he effect on stress intensity factor,a macro-element method to calculate stress intensity factor is simplified to analyze the variety of the stress intensity fa ctor under different crack eccentricity ratio.To generalize the eccentricity rat io effect on ultimate tensile strength of ductile plates, the elesto-plastic fin ite element method is undertaken and a mathematical transition expression of nor malized ultimate tensile strength of center-cracked,eccentrically cracked, edge- cracked plates is accordingly deduced.The poly-fit equation takes into account t he effects of the eccentricity ratio,yield ratio of material and the nominal cra ck length and gives satisfactory accuracy comparing to the experiment results.