初始裂纹尺寸对疲劳可靠性的影响(英文)

Effect of Initial Crack Size on Probability of Fracture Failure

疲劳是船舶、海洋工程和桥吊等钢结构的主要破坏机理之一。影响疲劳裂纹成长的因素具有随机性质。用Paris定律描述疲劳的扩展 ,假定疲劳裂纹初始具有半椭圆形状 ,且在裂纹扩展中保持着半椭圆形状。失效准则采用在具有N次应力周期的给定时间中裂纹超过临界尺寸。用Paris定律 ,结合改进的Ⅱ水平方法 ,对不同初始裂纹对断裂破坏的可靠度进行了分析计算。

Fatigue is one of the failure mechanisms of ship,offshore and bridge crane steel structures.The factors influencing the fatigue crack growth are of random nature.The Paris’ law is used for the description of crack propagation.It is assumed that the fatigue crack initially has a semi-elliptical shape,and that the shape remains semi-elliptical as the crack propagates.The failure criterion is taken as exceedance of a critical crack size in a time period with N stress cycles.To simplify the problem the thickness of plate is chosen as the critical size.Then using the Paris’ law in conjunction with an advanced Level II method,the reliability of fracture failure is examined.