Finite element analysis of a solid booster flexible bearing joint for thrust vector control

Purpose of the present work is to present the analysis, through a numerical approach, of the behaviour in operative conditions of a component of the thrust vector control of a solid rocket motor. This component, a laminated flexible joint, is a fundamental part of the thrust vector control system of such a kind of motors. It is devoted to interface the nozzle with the booster case introducing the flexibility necessary to allow the nozzle to follow the movements imposed by actuators in order to obtain a deflection of the jet flow. The scope of this component, constituted as a sequence of reinforcement and rubber layers, is to work as much as possible as a spherical joint with centre (pivot point) along the axis of the motor. Most of the difficulties encountered during the study are related to the convergence of the solution, due to the strongly nonlinear behaviour of rubber under pressure and actuation loads. A precise characterization of the constitutive laws of the rubber material under high compression stress state become fundamental when it is modelled as a quasi-incompressible media.