Abstract: When designing the structure of a certain solid propellant rocket motor’s rolling ball joint socket nozzle, the maximal swing angle, the excursion of swing center, and the driving moment must be within the design limits permitted, and moreover, system must bear the extreme working loads. Motion state of system components is complicated because of the contact and the collision among the rolling ball, convex sphere, concave sphere and the separator. To solve the key problem of the contact load-bearing property which decides the design of the system structure and functions into play, the elastomeric collision between the ball and the separator in the joint is simulated as a parallel nonlinear spring damper, and the mode flexibility of convex sphere and concave sphere are described by the finite element method model. At the same time, the elastic contact model between the rolling ball and the convex-concave sphere model is established by introducing the calculation result of the elastic-plastic frictional contact deformation. The rigid and flexible coupled multi-body dynamics model of the system is established based on the first kind of Lagrange dynamics equation. The swing disciplinarian, excursion of swing center and driving moment of the system are calculated and analysed. By contrast with the torque measured of the pendulous test and ignition test, the structural design of system, the dynamic modeling method and its result’s rationality are examined.

Key words: Dynamics analysis, Ignition test, Pendulous test, Rolling ball joint socket nozzle, Solid propellant rocket, Swing performance