典型加筋板结构面内裂纹偏转与扩展行为分析

为研究筋条截面形式和多部位损伤对整体加筋板裂纹偏转行为和断裂特性的影响，采用断裂力学和有限元方法对其进行分析.首先建立整体加筋板疲劳裂纹扩展模型，通过与裂纹扩展速率试验进行比较验证模型可靠性；在此基础上讨论筋条截面形式对裂纹断裂参量和转折行为的影响；最后对多裂纹问题进行研究.结果表明：筋条截面形式对断裂参量的影响并不显著，裂纹偏转行为在远离筋条区域扩展时发生的可能性最大；多裂纹情况下裂纹并不会转折，而是笔直扩展进而连通成一条大裂纹，同时由于相邻裂尖的强烈干涉，造成应力强度因子剧增，加速裂纹扩展，进而严重缩短了扩展寿命，因此需采用有效的修补手段来提高结构的剩余强度和使用寿命.
Using the fracture mechanics and finite element analysis theory, the effect of section types of the ribs and multiple-site damage on the crack turning behavior and fracture characteristics of the integral stiffened panel is investigated. First the crack growth model of the integral stiffened panel was established, and the reliability of the established model was proved in comparison with the test results of the crack growth rates. Based on the above model, the influence of section types of the ribs on the crack fracture parameters and crack turning was discussed. Finally the multiple cracks problem was investigated. The study showed that the effect of the sectional types of the ribs on the fracture parameters was not significant and the crack turning was more likely to occur when the crack was growing far away from the ribs. In the case of multiple cracks, cracks will not turn, but grow straightly and connect to form a large crack. Moreover, the strong interference of adjacent crack tips can lead to the severe increase of stress intensity factor and acceleration of the crack growth. Furthermore, the crack propagation life will be seriously shortened. Therefore, effective repairing methods are needed to improve the residual strength and service life of the structure.