低周疲劳载荷下考虑累积塑性的船舶裂纹板剩余极限强度研究

研究表明在恶劣海洋环境中船体结构整体断裂破坏往往是低周疲劳破坏和累积塑性破坏的耦合结果。考虑这两者耦合作用的影响,评估船体结构的极限承载力更为实际。基于累积塑性和低周疲劳裂纹扩展,从理论上分析了平面内低周疲劳载荷下裂纹板的残余极限强度。经过一系列数值模拟,首先讨论低周疲劳裂纹扩展行为的影响,然后随着疲劳裂纹扩展的发展,主要讨论了初始变形,焊接残余应力,裂纹扩展长度,裂纹分布和裂纹板厚度对低周疲劳载荷下船体裂纹板极限强度的影响。

Residual Ultimate Strength of Hull Cracked Plates Based onAccumulative Plasticity Subjected to Low-cycle Fatigue Loadings

It is shown that the overall fracture failure of hull structures is often the coupling result of low-cycle fatigue failure and progressive plastic failure in harsh ocean environment. Considering the coupling effect, the evaluation on the ultimate bearing capacity of hull structure is more practical. The residual ultimate strength of cracked plates subjected to the in-plane low-cycle fatigue loading will be analyzed theoretically on the basis of the accumulative incremental plastic deformation and the low-cycle fatigue crack propagation. After a series of numerical simulations, the effect of low-cycle fatigue crack propagation behavior is discussed firstly, and then with the fatigue crack propagation moving forward, the effect of the initial deformation, the welding residual stress, the crack propagation length, the crack distribution and crack plate thickness on the residual ultimate strength of cracked plates subjected to the low-cycle fatigue load are mainly discussed. Some useful numerical results are obtained in the end.