固体火箭发动机柔性接头摆动密封可靠性研究

柔性接头由弹性件与增强件交替粘接而成，是固体火箭发动机进行推力矢量控制的重要装置，因而柔性接头的摆动密封性能对固体火箭发动机而言至关重要。为研究固体火箭发动机柔性接头摆动过程中的密封可靠性，以内聚力模型作为粘接界面的本构模型，通过计算柔性接头各界面的损伤情况及界面间的接触应力，并定义界面节点单元间、界面间以及柔性接头的密封状态，结合可靠性理论提出了一种计算柔性接头摆动密封可靠度的方法。以某柔性接头为算例，分析了工作过程中容压和摆角对柔性接头摆动密封可靠度的影响规律。结果表明：柔性接头界面中，与后法兰粘接的界面最易发生损伤，同时密封可靠度也最低，而中间界面密封可靠度最高；当摆角在2°以内时，界面密封性能最佳，当摆角大于2°时，随着摆角增加，柔性接头密封可靠度呈迅速下降趋势，而当容压增加时，柔性接头密封可靠度呈现先减小后增大规律，容压2MPa左右下柔性接头密封可靠性最差。同时，界面间的剪切载荷是影响柔性接头摆动密封可靠度的主要因素。以上规律可对柔性接头的设计、计算分析提供依据。

Vector Sealing Reliability of Flexible Joint in Solid Rocket Motor

Flexible joint, a device that provides thrust vector control for some solid rocket motors, is a key component in solid rocket motor. Flexible joint is composed of alternately bonded elastomers and reinforcements. The vector sealing reliability of flexible joint is a pivotal factor affecting the operation of solid rocket motor. In order to investigate the sealing reliability of flexible joint, a cohesive zone model is selected as the constitutive model of interface in flexible joint. By calculating interfacial damage and contact stress, defining the sealing status of nodes, interfaces and flexible joint, and adopting reliability theory, one method is proposed to calculate the vector sealing reliability of flexible joint. Taking one flexible joint as an example, the effects of pressure and vector angle on the sealing reliability of flexible joint are analyzed. Results indicate that the interface bonded to the rear flange is most vulnerable to damage, and shows the minimum sealing reliability, while the middle interfaces have the highest sealing reliability among all the interfaces of flexible joint. The interfaces of flexible joint have the best sealing performance when the vector angle is within 2°. When the vector angle is larger than 2°, the sealing reliability of flexible joint decreases rapidly with the increase of vector angle. With the increase of pressure, the sealing reliability of flexible joint shows a downward tendency first and then increases. When the pressure is around 2 MPa, the sealing reliability of flexible joint reaches the lowest. At the same time, the shear force at the interface is the major factor that affects the sealing reliability of flexible joint. This study can provide a basis for the design, calculation and analysis of flexible joints.