应力加载路径对板壳塑性起皱失稳极限的影响研究

With the increasing requirements for the lightness and toughness of metal products in the manufacturing technology fields such as aerospace, aviation, national defense and automobile, plastic instability has become one of the problems restricting the overall forming of metal products. Therefore, it is of great significance to predict and prevent the wrinkling and instability defects efficiently and accurately in the forming process of thin-walled components. Tensile test of wedge-shaped part is taken as the research object. By establishing numerical buckling model of wedge-shaped part and combining with bifurcation principle, a numerical solution and drawing method of WLD is proposed. In view of the significant influence of the stress loading path on the wrinkling instability of metal plate and shell specimens during the forming process, the stress loading path in different areas of the wedge is analyzed to explore the influence of the stress loading path on the critical wrinkling limit during plate and shell deformation. The results show that WLD should be built established in different regions for specimens with independent wrinkling regions under different stress states. The influence of stress loading path in different regions on WLD can be summarized as the influence of the critical wrinkling principal stress ratio on the principal strain ratio: when the critical wrinkling principal stress ratio is larger, the critical wrinkling principal strain ratio is larger, that is, the slope of WLD is larger, and the process resistance is weaker. At the same time, by comparing the load bearing histories of different wrinkling instability zones of the wedges, it can be seen that the increasing rate of critical principal compressive stress during wrinkling will affect the critical wrinkling instability moment of the sheet metal.