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对压缩作用下的冷弯薄壁型钢进行非线性有限元分析(FEA)时,模型中需考虑初始扰动以免由于不稳定性而引起失效。最常用的方式是在模型(常规模型)中引入等效初始缺陷,包含由滚轧成型制作工艺、加载偏心率等引起的几何缺陷和残余应力的影响。如果引入制作过程中的实际测量的几何缺陷和残余应力,计算结果将更加准确。通过有限元模拟,给出了钢板在典型机架(未穿孔)滚轧成型制作过程中产生的残余应力和应变。然后,将得到的残余弹性和塑性应变纳入模型中,作为非线性有限元分析的初始应变状态。短柱和中长柱的有限元分析结果与试验结果吻合较好,其中失效模式以局部屈曲和畸变屈曲为主。
For nonlinear finite element analysis (FEA) of cold-formed thin-walled sections under compression, initial perturbations must be considered in the model to avoid failure due to instability. The most common approach is to introduce equivalent initial imperfections into the model (conventional model), including the effects of geometric defects and residual stress caused by the roll forming process, loading eccentricity, and the like. If we introduce the actual measurement of geometric defects and residual stress in the production process, the calculation results will be more accurate. Through the finite element simulation, the residual stress and strain of the steel plate during the rolling process of the typical frame (not perforated) are given. Then, the residual elastic and plastic strains obtained are incorporated into the model as the initial strain state of nonlinear finite element analysis. The results of the finite element analysis of the short column and the long column agree well with the experimental results. The failure mode is dominated by local buckling and distorted buckling.