径向带槽金属爆破膜结构非线性力学行为研究

STUDY ON NONLINEAR MECHANICAL BEHAVIOR OF RADIAL NOTCHED METALLIC RUPTURE DISCS

用于压力设备与管道超压安全泄放的安全阀不可能密而不漏 ,因而对有毒介质、稀有元素介质等场合常用爆破膜代替安全阀或采用爆破膜在前安全阀在后的组合式结构。但受侧向载荷作用的金属薄膜 (壳 )结构由于其几何及材料的非线性特点使得解析计算工作非常困难 ,目前其设计和制造主要依赖于实验。通过一个普通结构实例 ,基于TotalLagrange列式 ,对 5种类型壳元进行了几何及材料非线性耦合分析的考核 ,并选择其中的 4结点四边形混和壳元对径向带槽防爆结构进行了有限应变弹塑性有限元分析。结合实验结果发现 :等效应力的最大值出现在 10 %～ 2 2 %径向位置的沟槽根部 ;结构的极限载荷与槽底余厚之间存在着明显的线性关系 ;此外 ,带槽结构的极限载荷要明显小于厚度为槽底余厚的普通结构的极限载荷。最后从理论上对上述结论给予了解释。

Safety valves used in pressure vessels and pipelines for overpressure discharge may leak. So, the rupture discs are usually used to take the place of safety valves or the pattern of rupture discs placed before safety valves is used for the poisonous medium and the rare element medium. But for metallic diaphragms (shells) with lateral loads, their analytical calculation is very difficult due to the nonlinear behavior in both geometry and material. Therefore, the design and fabrication intensively depend upon experiments. With a real case of an average structure, and based on T. L. formulations, five kinds of shell elements had been verified for the analysis of nonlinear coupling in both geometry and material. Then the MITC4 shell element was selected for the finite element analysis of limit strain elasto-plasticity of radial notched rupture discs. With experiments, it is found that the maximum equivalent stresses are located at the 10% - 22 % of radial position on the root of notch. And there are remarkable linear relationships between the limit load and the thickness of shell on the notch. So, the limit load of notched shell is lower than that of ordinary shell with the same thickness because of the thickness on the notch. In the end, the article explains the above mentioned conclusion therotically.