高性能、高质量、大径厚比、轻量化大型薄壁燃料贮箱封头的整体化成形是目前我国航天制造急需解决的重大问题。通过旋压实验与有限元数字仿真相结合的方法对薄壁封头在小减薄率工况下的等壁厚旋压成形稳定性展开研究,在实验中研究了缩径旋压过程中封头法兰起皱失稳现象,并通过有限元仿真软件Marc分析了法兰起皱的演变过程。通过建立缩径位移等效模型,得出缩径位移量与法兰起皱有直接关系,即缩径量越大,法兰起皱越明显。对比仿真模型和等效模型的最大主应力矢量图,分析得出缩径会导致切向应力变化从而引起法兰起皱失稳,进一步证实了缩径是起皱失稳的主要原因。
The whole forming of large thin-walled spherical heads with high performance, high quality, large diameter-thickness ratio and light weight is an urgent problem to be solved for Chinese aerospace industry. Both experiments and finite element simulations were carried out to analyze the stability of spinning thin-walled spherical head at low thinning rate. The wrinkling in flange region was studied in the ex- periments, and the process of wrinkling during the necking spinning process was analyzed by software Marc. Further, by establishing the equivalent displacement model of necking spinning, the quantity of necking displacement was found to be directly related to the flange wrinkling, namely, the larger is the quantity of necking displacement, the more obvious is the flange wrinkling. Comparing the maximum principal stress vector calculated by simulation model and by equivalent necking displacement model respectively, it is found that the necking would being the changes of tangential stress which resulted in wrinkling in the flange region. Therefore, the necking is proved to be the main cause of wrinkling.