Research On Vibration Characteristic Of Human-Seat And Optimum Match Of Seat Suspension System Parameters For Engineering Vehicle

The engineer vehicles generally require high load capacity,and the condition for driving and working is much worser,the stiffness of suspension system in chassis usually need to be designed in hard,which lead to the result that the effect of buffer and damping is less reliable,the problem of cab vibration is very serious in the last.The seat suspension system can effectively reduce vibration and shock acting on human body from the cab floor and have little negative influence on the other riding performance of vehicle,which have been used widely in the engineer vehicles.However,in fact,human body and seat compose a complex and dynamic system,for the reason that the model is not accurate or the parameters are not appropriate selected for human body,it is hard to reach the best matching for the seat suspension parameters;Restricted by the throttle slice deformation,oil nonlinear analytic calculation of throttling loss and so on,there have not been accurate and reliable design methods for seat damper,it could be only designed approximately by doing experiment repeatedly and simulating in the software.In this paper,some research were conducted aiming at the problems,the research task are as follows:(1)According to the three-DOF vibration model of human-seat,the data of amplitude frequency characteristic were acquired through driving test,which was used to develop the mathematical model based on least square method,all parameters of the model were identified by using nonlinear optimization function in Matlab software;By building the simulation model for human-seat and taking the test data of floor vibration acceleration as input,the accuracy of model and the results and method of identification were validated by comparing and analysing the acceleration and power spectral density of seat between the simulation and the test.(2)Selecting the limit travel of suspension,the natural frequency and the damping ratio of seat system as the constraints,a multi-objective optimal model was established by taking the minimum weighted root mean square of acceleration of seat and the root mean square of deflection of suspension as the optimization objectives for optimizing the parameters of seat suspension system;the Kriging approximation models were constructed based on optimal Latin hypercube design for the parameters of optimization and analysis,in which the parameters of human body and cushion were taken as uncertain values and the parameters of seat suspension system were taken as optimization variables On this basis,multi-objective opmization for parameters of seat suspension was performed by the improved genetic algorithm NSGA-?,The accuracy of the optimization results were verified in final by comparing the acceleration of seat and deflection of suspension before and after optimization.(3)According to the elasticity theory,the deformation analytic formula of annular throttle slice under non-uniform pressure was established.On this basis,for the relation between oil flow and throttling pressure when valves opened,etc.The active design mathematical models and methods were established about the area of constant throttling orifice and the thickness etc for the rebuilt valves and the compression valves based on velocity of golden section method.A shock absorber sample was designed for testing the characteristic indexes of it,the result proved the design method was accurate.the good performance of the seat suspension after optimal match was tested in road experiment,which showed the dynamic comfort of seat and the simplicity of operation were all improved evidently,which indicated the optimal results were trustworthy.the researchs have great theoretical significance and practical value for the design and develop of the comfortable system of seat.