循环弯矩下考虑弹性安定特性的某散货船极限强度研究

Research on the ultimate strength of a bulk carrier considering elastic shakedown under cyclic bending moment

  • 摘要: 【目的】为准确评估船体梁在循环弯矩下的总纵极限强度,研究理想弹塑性与Chaboche材料模型对循环弯矩下船体梁弹性安定与极限强度的影响。【方法】通过非线性有限元法,对某双底散货船开展了循环弯矩下考虑弹性安定特性的极限强度数值模拟计算。研究中考虑了船体结构在反向加载时材料的包辛格效应,焊接初始变形与残余应力的影响。【结果】结果显示焊接初始缺陷会明显降低散货船船体梁的弹性安定下限,考虑焊接初始变形与残余应力的散货船船体梁弹性安定区间范围最大。循环弯矩下达到弹性安定状态后,考虑完整焊接初始缺陷的散货船船体梁在中拱、中垂状态下的极限强度比单次加载下的分别提升了7.15%和5.68%。【结论】焊接初始缺陷对散货船船体梁的弹性安定区间以及弹性安定极限强度有显著影响,在实际研究分析中应当仔细考虑。

     

    Abstract: Objectives In order to evaluate the longitudinal ultimate strength of hull girder under cyclic bending moment accurately, the effects of elastic-perfectly plastic and Chaboche material model on the elastic shakedown and ultimate strength of hull girder under cyclic bending moment are studied. Methods Through the nonlinear finite element method, the ultimate strength numerical simulation of a double bottom bulk carrier considering the elastic shakedown under cyclic bending moment is carried out. In this study, the Bauschinger effect of the material during the reverse loading of the structure, the influence of the welding initial deformation and residual stress were considered. Results The calculation results show that the welding initial imperfections will significantly reduce the lower limit of elastic shakedown of bulk carrier, and the range of elastic shakedown of bulk carrier considering welding initial deformation and residual stress is the largest. After reaching the elastic shakedown under cyclic bending moment, the ultimate strength of bulk carrier considering the welding initial deformation and residual stress under hogging and sagging state is 7.15 % and 5.68 % higher than that under single loading, respectively. Conclusions The welding initial imperfections have a major impact on the elastic shakedown interval and the elastic shakedown ultimate strength of the bulk carrier, which should be carefully considered in the actual research and analysis.

     

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