Dynamics design for complex mechanical systems has become an important research field and development direction at present, capturing attentions of an increasing number of engineers and scientists worldwide. Based on many advantages of the transfer matrix method for multibody system in studying multibody system dynamics, a design problem of a multiple launch rocket system is solved in this paper. Particular attention is addressed to model actions of the exhaust flow on the multiple rocket launcher, which are associated with firing order and firing intervals of rockets. Combined with a genetic algorithm, firing order and firing intervals are optimized to achieve optimum impact point dispersion reduction. The results of numerical simulation and verification tests show good agreement, while the dispersion characteristics of rockets have been improved in a low-cost way.
To provide sufficient damping torque performance for heavy tracked vehicle's suspensions, the design of a novel high-torque rotary magnetorheological (MR) damper with a parallel plate channel, referred to as PPCRMRD, is presented and the prototype of the PPCRMRD is manufactured. The theoretical model of the PPCRMRD considering the Hybrid magnetic fields effect and leakage effects is proposed. The max damping torque and controllable damping torque of the PPCRMRD are tested on the established experimental setup based on MTS rotary test system and compared with the theoretical results based on the proposed theoretical model, the theoretical model ignoring leakage effect and Bingham plastic model respectively. Under the sinusoidal excitation of 0.05 Hz and amplitude of 35°, compared with the theroetical model without considering the leakage gap and the Bingham plastic model, the maximum error of the proposed model is reduced by 11.08% and 40.66%. The tested max damping torque and controllable damping torque of the PPCRMRD under sinusoidal excitation with an amplitude of 35°and frequencies of 0.1 Hz are as high as 2677 and 1711 N m. The research results show that the principle of the PPCRMRD can provide sufficient damping torque as well as a wide range of controllable damping torque and the proposed theoretical model of the PPCRMRD can describe and predict its damping torque performance precisely.
The purpose of this paper is to present a comprehensive multibody system dynamics model of a multiple launch rocket system (MLRS), and implement its simulation and experimental studies. The new version of transfer matrix method of multibody system and the launch dynamics theory are used in deriving the equations of motion coupled with rockets and barrels. The obtained model accounts for the complete process of the rockets’ ignition, movement in the barrels, airborne flight and landing. Launch dynamics of an 18-tube 122mm MLRS is investigated in this paper. Considering the effects of random factors, such as the impact and clearance between the rockets and barrels, the mass eccentricity and dynamic unbalance of the rockets and the thrust misalignment in this model, and combining the Monte Carlo method, the simulation of the dynamics of MLRS is carried out. Finally, the experimental implementation is proposed and the experimental results emphasize the feasibility of the multibody system launch dynamics model as a viable alternative for modeling accurately the dynamics characteristics of a practical MLRS. Meanwhile, the correctness of the numerical results is validated.
Multiple Launch Rocket System (MLRS) has been widely used in recent years; vibration control in launching process is an effective way to improve its dispersion characteristics. In this paper, a novel vibration control system applying Annularly Arranged Thrusters (AAT) for MLRS in launching process is introduced and the prototype of the proposed system is built. The dynamic model of the MLRS with the AAT is established based on the Transfer Matrix Method for Multibody Systems (MSTMM). The LQR-PID control law and the management for the AAT are presented. The simulation and experiment of the proposed system are carried out and analyzed. The results show that the vibration of MLRS is effectively attenuated by the proposed control system. The study in this paper provides a new idea to improve the dispersion characteristic by reducing the vibration of MLRS in launching process.
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