双母线椭球壳液压胀形过程应力与变形分析

发布时间：2018-08-24 19:05

【摘要】：通过设计双母线椭球壳作为胀形前预制壳,解决了初始轴长比大于2的椭球壳在胀形过程赤道带起皱的问题。为分析双母线椭球壳胀形过程的应力与变形特点,进行初始轴长比为1.5和1.7的双母线椭球壳液压胀形试验研究和数值模拟。通过数值模拟,揭示双母线椭球壳无模胀形避免起皱的机理。在变形过程中,赤道带板料一致承受双向拉应力作用;赤道带焊缝处在变形初始阶段存在纬向压应力,产生的原因是焊缝处多面壳体二面角展开过程存在弯曲效应,在焊缝外表面带来附加压应力,该压应力不足以引起失稳起皱;随压力升高,壳体各处均受双向拉应力作用。通过试验研究,绘制典型点的应力轨迹图,揭示双母线椭球壳胀形过程中塑性变形发展及壁厚变化规律。极带最先发生塑性变形,随着压力的升高,塑性逐渐向赤道线方向发展,赤道线最后发生塑性变形;壳体侧瓣中心线比焊缝线更容易发生塑性变形。极带的变形量大于赤道带,所以壁厚的最大减薄位于极点,最大减薄率分别为10.4%和16.3%。最终获得合乎设计要求的椭球壳。
[Abstract]:By designing double generatrix ellipsoidal shell as prefabricated shell before bulging, the wrinkling problem of ellipsoidal shell with initial axial length ratio greater than 2 in the equatorial zone of bulging process is solved. In order to analyze the stress and deformation characteristics of double generatrix ellipsoidal shell during bulging process, hydraulic bulging test and numerical simulation of double generatrix ellipsoidal shell with initial axial length ratio of 1.5 and 1.7 are carried out. The mechanism of avoiding wrinkling in die-free bulging of double-generatrix ellipsoidal shells is revealed by numerical simulation. During deformation, the equatorial strip is uniformly subjected to bidirectional tensile stress; the equatorial strip weld is subjected to zonal compressive stress at the initial stage of deformation, which is caused by the bending effect during the dihedral angle unfolding of the polyhedral shell at the weld, and the weld appearance. With the increase of pressure, the shell is subjected to biaxial tensile stress everywhere. The stress trajectory of typical points is plotted through experimental study, which reveals the development of plastic deformation and the variation of wall thickness in the bulging process of double generatrix ellipsoidal shell. The deformation of the polar zone is larger than that of the equatorial zone, so the maximum thinning of the wall thickness is at the pole, and the maximum thinning rate is 10.4% and 16.3% respectively.
【作者单位】：哈尔滨工业大学材料科学与工程学院;哈尔滨工业大学金属精密热加工国家级重点实验室;
【基金】：长江学者和创新团队发展计划资助项目(IRT1229)
【分类号】：TG394

【参考文献】