Dynamic Simulation And Optimal Design For The Vibration And Noise Reduction Of The Gear-Box

To reduce the vibration and noise of the gear-box structure, the damping layer and constraint layer are pasted on the surface of thin shell, forming the constraint damping structure. Due to the complication of the gear-box model,the arched plate structure which arises the most serious vibration and noise, is isolated from the gear-box to reduce the computing amount. The constraint layer and the damping layer are pasted on the inner surface of the arched plate. The boundary conditions are simplified. The dynamic simulation of the arched plate structure is made based on ABAQUS, and the optimal designs for the most effective structure of vibration and noise reduction and the most economical structure of cost are made in the allowable ranges of the thickness of each layer of the constraint damping. The optimization of the vibration acceleration level with the mass condition and the optimization of cost with the vibration acceleration level condition are obtained respectively. The main researches are summarized as follows:(1) The optimal design for the most effective structure of vibration and noise reduction. The design variables are respectively the thickness of basic layer, the thickness of damping layer and the thickness of constraint layer in the constrained damping structure; the designing constraint is to meet the total mass requirement; the objective functions are minimizing the normal maximal vibration acceleration of a few nodes on the structure, establishing the optimal model of the most effective structure of reducing vibration and noise, which is a multiobjective optimization. The K-S function is adopted to process the normal maximal acceleration of all representative points as a synthesis parameter, with the vibration acceleration level of it as the evaluation parameter for effect of reducing vibration and noise. The response surface methodology is used to explicit the vibration acceleration level function. The new model with a signal objective of the vibration acceleration level of the structure is obtained, which is solved by the sequential quadratic programming stably and gives out the more ideal structure.(2) The optimal design for the most economical structure of cost. As the structure of the same size, the cost of processing the damping layer and the constraint layer is fixed, which could be out of considering. The material cost of the structure is the only to be think about. Thickness of each layer of the constraint damping structure are taken as design variables; meeting upper limit of the vibration noise required by the environmental standards is the designing constraint; establish the most economical structure optimization model, which is a linear programming optimization. Reciprocals of the designing variables are used as the new designing variables. The constraint of vibration acceleration level is explicated as the function of the reciprocal variables with the response surface methodology. The objective function of the reciprocal variables can be lunched as the second-order Taylor function. The standard model of sequential quadratic programming is obtained and solved. The convergence speed of the optimal program is fast. The most economical structure satisfying the performance condition is also obtained.(3) Response surface methodology(RSM) is the curve fitting of the relationship between the inputs(variables) and outputs(responses) of a physical system by explicit functions. For RSM function of the first fitting, tests and fitting precision are made to improve the fitting accuracy and the fitting efficiency.