冷成型钢截面残余应力的有限元分析

冷成型钢截面上的残余应力可能是决定其性能和强度的一个重要因素。通过破坏性的试验方法对残余应力进行测量不仅费时,精度也很有限。本文提出了一个预测压弯成形薄壁截面上残余应力的有限元方法,该方法克服了实验室测量的缺点,提供了一个有力的工具来考察不同的成形参数对残余应力的大小和分布的影响,并因此可以对这些成形参数进行优化。在该方法中,通过解析的方法考虑了成卷和开卷的影响,并将得到的残余应力作为随后的冷弯过程有限元模拟的初始应力。经比较,本文方法的数值结果和实验室实测值吻合很好,证明了该方法的可行性和精度。本文方法给出了整个截面残余应力的分布和沿壁厚的变化,并解释了两个相同截面中残余应力可能会存在很大差别的原因。

Finite Element Predictions of Residual Stresses in Cold-Formed Steel Sections

Residual stresses in cold-formed sections may play a significant role in determining their behaviour and strength.Laboratory measurements of residual stresses by destructive methods are not only time-consuming but also of limited accuracy.This paper describes a finite element-based method for predicting residual stresses in press-braked thin-walled sections,which overcomes these difficulties.The method offers a powerful tool for exploring the effect of different forming parameters on the magnitude and distribution of residual stresses,so that these forming parameters can be optimized.In this method,the effects of coiling and uncoiling are accounted for analytically,with the resulting residual stresses specified as initial stresses in a subsequent finite element simulation of cold bending.Numerical results from this method are shown to agree closely with laboratory measurements,demonstrating the validity and accuracy of the method.The present method provides residual stress distributions over the cross-section as well as across the thickness,and also explains why residual stresses may differ considerably in otherwise identical sections.