考虑几何缺陷的刚架结构力学性能研究

Research on physical properties of frame structure with geometrical imperfection

以吊船大型刚架结构为研究对象,采用多单元混合的局部精细化有限元模型,兼顾精度要求和计算效率,在有限元分析中同时考虑结构的几何和材料非线性;通过特征值屈曲分析,研究初始几何缺陷对刚架结构的力学性能影响;通过改进一致缺陷模态法中直接以最低阶屈曲模态作为缺陷分布的方法,计算分析获取最不利几何缺陷作为结构初始几何缺陷分布,对结构进行稳定性评估;结合工程经验,对架体结构几何缺陷作正态分布假设的拟合,验证了上述方法的正确性和可靠性。表明:该结构对初始几何缺陷敏感,考虑几何缺陷的结构稳定性能是完善结构的30%~40%,对几何缺陷确定,应该分析比较不同几何缺陷分布模式以确保结果的合理性和可靠性。

Analyzed the model of frame structure, in order to obtain a efficient and reliable mechanical performance assessment method for it. Balanced the accuracy and computational efficiency, established the mixed finite element model,considered the geometrical and material nonlinearity in finite element analysis. To account for geometrical imperfection of frame structure effect, carried out eigen buckling analysis, selected the most unfavorable geometrical imperfection instead of utilizing the minimum order buckling mode as geometrical imperfection, and then calculated the frame structural stability.The stochastic imperfection method result verified the correctness and reliability of the above method. Calculations showed the frame structure was sensitive to initial geometrical imperfection, the stability coefficient considering the initial geometrical imperfection was round 30%~40% of perfection structure. For the sake of the reasonable geometrical imperfection, analyzed and compared different geometrical imperfection distribution patterns were necessary.