椭球壳液压胀形过程焊缝建模方式的研究

为了研究焊缝区域有限元建模方式对椭球壳胀形过程轴长变化规律的影响,提出3种焊缝建模方式:即完整焊缝模型,粗略焊缝模型与无焊缝模型。首先进行初始轴长比为1.8的椭球壳的液压胀形实验研究,得到轴长随内压力的变化规律。其次进行了3种建模方式的椭球壳胀形过程的数值模拟,对比数值模拟和实验过程轴长变化规律,分析建模方式对模拟精度的影响。结果表明:在变形初期,3种建模方式的模拟精度相近,尺寸偏差均小于4%;但是在变形中后期,无焊缝模型的模拟精度较差,最大尺寸偏差达15%;粗略焊缝模型和完整焊缝模型都能较好地预测轴长的变化规律,且尺寸偏差不超过5%。综上所述,粗略焊缝模型既能简化建模方式,又能较好地预测椭球壳胀形过程轴长的变化规律。

Research on Weld Seam Models for Hydro-forming of Ellipsoidal Shell

In order to study the effect of weld seam models on hydro-forming of ellipsoidal shell,three kinds of models,i.e.,comprehensive model rough model and no weld seam model were built and the influence was discussed on variation of axis length.An experiment for hydro-forming of ellipsoidal shell with initial axis length ratio 1.8 was first carried out,and the axis length varying with the increasing of internal pressure was obtained.Simulation on three kinds of finite element model was conducted,and the effect of weld seam models on the simulation accuracy was deeply discussed by a comparison of axis length variation between simulation and experiment.It is shown that little difference happens among the three kinds of weld seam models at the early stage of deformation,and the axis length deviation is less than 4％.However,there is worse simulation accuracy for the no weld seam model at the middle and late stage of deformation,and the axis length deviation is up to 15％.While both the comprehensive model and the rough model can successfully predict the axis length variation with the deviation no more than 5 ％.Finally,the rough model is selected on the basis of better simulation accuracy and simple weld seam model.