基于FIP的焊趾短裂纹行为仿真

变幅载荷作用下的疲劳寿命预测一直是焊接结构完整性评估的重要内容. 基于Pavlou提出的疲劳损伤区概念，采用BS7608标准中推荐的S-N曲线，运用有限元热传导分析技术，提出了一种焊接结构疲劳寿命的预测方法. 针对承载型十字焊接接头、非承载型十字焊接接头和对接焊接接头，开展了二级变幅载荷谱块的拉伸疲劳试验，分别采用Miner模型、M-H模型和Pavlou方法估算了试件的疲劳寿命. 结果表明，Pavlou方法的预测精度明显高于其它2种模型，预测寿命与试验寿命误差散射图中数据点的分布形态更加合理，验证了Pavlou方法的精确性和有效性. 进一步讨论了焊接接头S-N曲线存活率对疲劳寿命预测精度的影响，提出2.3%存活率可以获得较为满意的预测结果.

Simulation of short crack behavior of welding toe based on FIP

Fatigue life prediction under variable amplitude loading is an important issue in the integrity analysis of welded structures. Based on the fatigue damage zone concept proposed by Pavlou and the S-N curve recommended in BS7608 standard, an approach to predict fatigue lives of welded structures was realized by FEA heat transfer problem. Fatigue tests under two-level tensile loading block sequences were conducted for load-carrying cruciform welded joints, non-load- carrying cruciform welded joints and butt welded joints, respectively. The fatigue lives of the specimens were estimated according to Miner model, M-H model and Pavlou method. Results showed that the Pavlou method had higher prediction accuracy with more uniform distribution in the error scatter diagram of predicted life versus test life, which validated the rationality and effectiveness of the proposed method. Moreover, the influence of S-N curve survival probability on the life prediction accuracy is discussed. The S-N curve with 2.3% survival probability is suggested to be utilized to obtain satisfactory prediction results.