Multibody Dynamics Modeling and Simulation of Supersonic Flexible Rocket Sled-Track Systems

To enhance the accuracy of predicting the dynamic response of a supersonic rocket sled along a multikilometer track, a multibody dynamics model of a flexible sled-track system was formulated using finite volume beam elements and multi-degree-of-freedom spring-damper joints. Shear locking was avoided by modifying the constitutive matrix, and the accuracy of the modeling method was validated through modal tests of both the sled and the track. The sled-track interaction model was developed by considering clearance, collision, and friction. A window transfer method was developed to improve computational efficiency. The flexible sled, with a maximum velocity of Mach 2.7, was simulated running along the long flexible track, accounting for the sled's time-varying mass, random track irregularities, oscillating engine thrust, and velocity-dependent aerodynamic forces. A supersonic rocket sled test was also conducted to validate the method. The results showed that the flexible sled-track model developed in this study significantly improved the accuracy of predicting the system's dynamic response compared to traditional rigid sled or track models. The main frequencies of the sled cabin's dynamic responses corresponded to the system's time-varying natural frequencies. The slipper's acceleration exhibited superharmonic responses, with the main frequencies being odd multiples of the fundamental frequency.