Abstract：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.
2021, Vol. 42 
