焊管液压成形极限的数值仿真分析

建立了反映焊缝、热影响区和母材3部分结构的焊管有限元模型，采用应变增量比作为数值仿真中的颈缩判据，计算出液压成形条件下QSTE340焊管的成形极限曲线，并利用数值仿真的工艺路径完成了QSTE340焊管成形极限的实验测定.结果表明，数值仿真所得成形极限曲线与其实验值较为吻合，最先发生颈缩的位置位于紧邻焊接区的母材单元上，与其实验观察的颈缩发生位置相一致，从而验证了所提数值仿真方法的可靠性.

Numerical Analysis for Forming Limit of Welded Tube in Hydroforming

The model of electric resistance welding (ERW) tube, which reflects welded seam, heat affected zone and base material, was built up in finite element simulation. The ratio of strain increment was adopted as a necking criterion of tube in hydroforming numerical simulation. Furthermore, using the above method, the forming limit curve of QSTE340 ERW tube was determined. The corresponding forming limit test of QSTE340 ERW tube was completed using the processing path calculated form numerical simulation. Compared with the experiment the forming limit curve obtained by this method is in agreement with the experimental data. It is proved that the hydroforming forming limit of welded tube calculated based on numerical simulation is believable.