薄板的后屈曲损伤分析与疲劳寿命预估

针对薄板在面内压缩载荷作用下的后屈曲损伤问题进行了研究,并进一步考虑屈曲与疲劳损伤的耦合作用,预估了薄板的疲劳寿命.首先建立了薄板的有限元模型,通过线性屈曲分析得到屈曲临界载荷和屈曲模态,进而采用大变形理论,将线性屈曲的一阶屈曲模态作为初始位移扰动,进行薄板的非线性屈曲分析,得到屈曲临界载荷.其次,根据损伤力学理论与方法建立了薄板材料在单次加载过程中的损伤演化方程,并根据材料疲劳试验结果进行参数识别,获取损伤演化参数.根据非线性屈曲分析结果和损伤演化方程进行了后屈曲损伤分析.最后,考虑疲劳载荷的作用,基于损伤力学理论,采用有限元数值方法求解,考虑每次加载引起的损伤与后屈曲应力应变场分析的耦合作用,通过反复迭代计算,给出了结构疲劳寿命.本研究为工程结构的后屈曲损伤分析以及考虑后屈曲损伤的疲劳寿命分析提供了一种新方法和实现手段. 

Post-buckling damage analysis and fatigue life prediction of thin plate

Post-buckling damage of thin plate under compressive load in plan was studied, and the fatigue life of plate was predicted by taking the coupling effect of buckling and fatigue damage into account. Firstly, the finite element model was established, and the critical buckling load and buckling mode were obtained by linear buckling analysis, then the large deflection theory was adopted, first order buckling mode was applied as the initial displacement perturbation, and the corresponding critical buckling load was determined by nonlinear bucking analysis of thin plate. Secondly, damage evolution equation of thin plate material under monotonic loading was established based on damage mechanics theory and method, and parameters of damage evolution were obtained by the parameter identification based on the material fatigue test results. Post-bucking damage was analyzed base on nonlinear bucking analysis results and damage evolution equations. Finally, the effect of fatigue load was took into consideration, finite element numerical method was used to solve the problem based on damage mechanics theory, considering the coupling effect of the damage caused by load each time and post-bucking stress strain fields analyze, the fatigue life of the structure was achieved by repeating iterative computations. The research provides a new method and a practical means for the analysis of post-buckling damage and fatigue life considering post-buckling damage of engineering structures.