薄壁槽形截面压杆弹性整体屈曲数值计算研究

为研究薄壁槽钢整体屈曲下的数值算法的适用性,以4种不同杆端约束下的薄壁槽形截面压杆为研究对象,根据广义梁理论确定其发生弹性整体屈曲的有效长度及临界荷载,与开口薄壁理想压杆的线性及非线性解析解进行对比,得到一致的临界荷载。利用ABAQUS有限元分析软件建立壳体有限元模型,采用杆端截面形心集中加载,依据约束情况确定杆端约束,以及根据有效长度施加不同初始缺陷的计算模型,开展特征值算法和隐式弧长法数值计算分析。计算结果表明:当开口薄壁压杆的有效长度足够大时,临界荷载的特征值数值解与理论解一致,弧长法计算得到的非线性解误差相对较大。当有效长度不够大时,弧长法计算得到的极限荷载与理论解基本一致,且弧长法可有效追踪后屈曲路径。

Numerical Study on the Elastic Overall Buckling of Thin-Walled Channel Compressive Members

In order to study the applicability of a numerical algorithm for overall buckling,four thin-walled compressive channels with different end constraints are analyzed in this paper.The effective lengths and critical loads of compressive channels under overall buckling are determined according to the generalized beam theory(GBT),and the results are compared with the linear and nonlinear analytical solutions of ideal thin-walled open-section compressive members.Finite element analysis is conducted using ABAQUS,in which the shell element models with axial loads applied at centroids,different end constraints and initial defects according to the effective lengths are considered.The generalized eigenvalue method(GEM)and the implicit arc-length method(ALM)for buckling analysis are carried out.The results indicate that critical loads calculated by GEM are consistent with the analytical results when the compressive members have enough effective lengths,but the nonlinear solution errors calculated using ALM are relatively large.When the effective lengths are not large enough,the ultimate loads determined using ALM are almost consistent with analytical results,and the post buckling behavior can be clearly traced using ALM.