铝垫片的力学性能及对典型连接结构应力分布的影响

Study on mechanical properties of aluminum gasket and its effect on stress distribution of typical connection structure

铝垫片-榫槽结构是液体火箭发动机常用的管路连接形式,其长期贮存密封性能对发动机的可靠性起着重要作用。该结构的密封性能取决于密封区的应力分布,从铝垫片这一连接结构中的主要密封元件着手,研究其力学特性及其对密封区应力分布的影响。首先,开展L4铝垫片材料的力学性能试验,建立了L4铝材料的本构关系;其次,开展常温及200℃下L4铝材料的蠕变试验,建立铝垫片的时间硬化型蠕变模型;最后,使用Abaqus有限元软件分析5~25 N·m预紧力矩下垫片的应力分布规律,以及垫片密封面接触压力随时间变化关系。计算结果表明,垫片的应力分布与装配预紧力矩紧密相关;材料的蠕变特性会导致垫片密封面接触压力随时间松弛,是造成结构泄漏的一个重要隐患。

Tenon-mortise and gasket joint is a frequently used pipeline connection structure for liquid rocket engine,and its long-term storage sealing performance plays an important role in engine reliability.The sealing property of this structure depends on the stress distribution in the sealing zone.This paper starts with the main sealing component in the connection structure of aluminum gasket,and studies its mechanical properties and their effect on the stress distribution in the sealing zone.Firstly,the mechanical performance test of L4 aluminum gasket material was carried out,and its constitutive relation was established.Secondly,the creep test of L4 aluminum was conducted at room temperature and 200℃,so as to establish a time-hardening type creep model of aluminum gasket.Finally,Abaqus finite element software was used to calculate the stress distribution of gasket under the prestressing moment of 5~25 N·m,and obtain the relationship between the contact pressure of gasket sealing surface and time.The calculation results show that the stress distribution of gasket is closely related to the pre-tightening moment;the creep characteristic of L4 Al will cause the contact pressure of gaskets sealing surface to relax with time,which is a significant risk of structure leakage.