材料模型对弯管壁厚变化有限元仿真的影响

为研究材料模型对管材弯曲变形的影响,将管材拉伸试验所得真实应力应变曲线分别拟合成线性硬化和指数硬化材料模型,并用于有限元仿真。经对比分析认为,以真实应力应变曲线为加载曲线,对航空1Cr18Ni9Ti弯管壁厚变化的有限元计算与试验结果吻合程度最好;采用线性强化材料模型的仿真精度,高于指数硬化模型仿真精度。弯管壁厚变化主要集中在弯曲中段,弯、直管段交界处的变形缓和效应,使弯管两端壁厚变化逐渐减小,并且使未发生弯曲变形的直管部分也产生一定量的壁厚变化。

Analysis on the effects of material models on wall thickness variation of tube bending based on numerical simulation

The true stress-strain curve derived from the tube tensile test is fitted to dual-linearity material model and power exponent hardening model,for computing wall thickness variation of 1Cr18Ni9Ti tube with finite element simulation.Through comparison and analysis,following conclusions can be made:1)By taking the true stress-strain as the load curve of finite element simulation,the coincidence of the calculation results with the experimental results is the most satisfactory.Besides,the results derived by using dual-linear material model are more accurate than using power exponent model.2) Wall thickness variation is primarily located at middle section of bent tube.The deformation easing effect at the connection border of the bent tube and straight tube causes the gradual decrease of the wall thickness variation of the bent tube at the tube ends.Certain extent of wall thickness variation also occurs at straight tube.