A novel method for the fracture reliability of welded structure was established through combining the line-spring model of surface crack with importance sampling method. The fracture reliability of typical welded plate was analyzed with this method in consideration of the uncertainty of parameters such as material character, external load, residual stress and crack size. The failure probability and reliability sensitivity were obtained. The example indicates that the fracture toughness KIC has the greatest effect on the structure reliability, external load N takes the second place, and Poisson's ratio v has the lowest. The accuracy and efficiency for rapid fractural assessment in engineering are demonstrated through comparing the results with those obtained by the direct Monte Carlo method.%将表面裂纹断裂分析的线弹簧模型法与重要抽样法相结合,提出了一种可进行焊接结构断裂可靠性分析的新方法.采用该方法对典型焊接平板的断裂可靠性进行了分析,分析过程中考虑了材料特性、外载荷、焊接残余应力、裂纹尺寸等参数的不确定性,给出了结构的失效概率以及各随机变量的可靠性灵敏度,算例表明,断裂韧度KIC对结构可靠性影响最大,外载荷N次之,泊松比v最小.与直接Monte Carlo法结果进行对比,表明该方法简便有效,精度高,计算量小,特别适合于工程快速断裂可靠性分析.
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