Study On Flexible Multi-Body Dynamics And Overall Parameters Optimization For Large Caliber Vehicle-Mounted Howitzers

Dynamics problem of truck-mounted howitzer in firing is studied by the theory of flexible multi-body dynamics, and the overall structure parameters of howitzer system is optimized by means of sensitivity analysis and optimization theory, which can provide theoretical foundation and design decision for overall design and structural design of such weapon systems.In term of the physical characteristics of gun launch, the modeling of flexible bodies system dynamics is investigated for truck-mounted howitzer by the method of the first kind of Lagrange's equations. The elastic deformation of part is described by the modal superposition of constraint modes, Craig attachment modes and Krylov Lanczos modes of substructure. The node-to-surface contact/impact dynamics is represented to model the 3D contact/impact between rigid bodies. The Bekker model is constructed to deal with the contact between soil and spade/wheel, in which the complicated factors such as elasticity and plasticity of soil, the sinkage of soil under loading or unloading are taken into consideration. The numeric computation for differential equations of flexible bodies system dynamics is discussed.The dynamics model of flexible bodies system is set up for a truck-mounted howitzer during firing, in which both the barrel and the upper carriage are treated as the flexible bodies. The connection between the flexible body and other objects is implemented by interface points defined by master and slave nodes, and then the coupling between rigid and flexible bodies can be successfully integrated. The mathematical models of bore force and forces generated by recoil mechanism, recuperator and equilibrator are formulated for launch load of truck-mounted howitzer, and the specific codes for such forces are developed, and finally transformed into dynamic link library, through which the user program can be incorporated with ADAMS package. The comparison between the predicted dynamics response and the tested data is conducted, and then the model and the simulated results can be validated.The sensitivity analysis model for flexible bodies system dynamics of truck-mounted howitzers is built by the variation method. The effects of overall structure parameters on the muzzle disturbance when projectile at exit are examined, including the clearance between tube and cradle, the position of front ferrule and rear ferrule, the layout of traverse rotation center, the longitudinal position of the spade center, the mass eccentricity of the recoil parts, the equivalent stiffness and damping, and the mass of the main parts. Parameters which take great effects on the muzzle disturbance are figured out, which can be of importance in optimization design of the overall structure parameters.In light of analysis on classical optimization of State Space method and Projected Gradient method, and characteristics of dynamics optimization for flexible bodies system dynamics of truck-mounted howitzers, the Genetic Algorithm (GA) is proposed for optimization of overall structure parameters of gun system. The GA for Multi-Objective Optimization(MOO) is derived by Pareto optimal approach. The Solver-Based-Simulation and data base of ADAMS is developed, and the dynamics optimization is performed for flexible bodies system dynamics of truck-mounted howitzers by use of Niched Genetic Algorithm (NGA) and ADAMS Solver. Upon completion of the optimization for the overall structure parameters, the muzzle disturbance can be obviously reduced, which can illustrate the necessity and importance of optimization for overall design proposal of gun system.