| The shock absorber is an important part of the vehicle suspension system,which directly affects the vehicle performance such as riding comfort and handling stability.After a long period of use,it was found that the traditional shock absorber cannot match the shock caused by different road excitations well.Therefore,it is particularly important to develop a variable damping shock absorber with adjustable damping characteristics and simple process.In this paper,a set of damping adjustment mechanism was designed to improve the existing shock absorber,and the damping characteristic analysis was performed to predict the work.The pros and cons of performance are specific from the following aspects.First,based on the working principle and structure of the original double-tube hydraulic shock absorber,the key components of the damper damping adjustment mechanism and connecting rod were designed;by establishing a mechanical model of the throttle valve,and using a circular thin plate The theory of elastic mechanics,combined with the differential equation of the throttle valve deformation and the boundary conditions,solves the deformation of the valve blade under the load;this provides a theoretical support for the subsequent establishment of the mathematical model of the shock absorber.Secondly,based on the theory of gap flow and slender orifice throttling in hydrodynamics,according to the two conditions before and after the opening of the throttle valve,a mathematical model in the process of the recovery stroke and compression stroke of the shock absorber was established,and then in MATLAB / Simulink In the simulation environment,the damper model was built and the dynamic characteristics were simulated and analyzed.The speed characteristic curve and the indicator characteristic curve at the same frequency and different gears and different frequencies and the same gear were obtained respectively;this is to predict the performance of the shock absorber The pros and cons laid the foundation.According to the "QC / TC491-2018 Automotive Shock Absorber Performance Requirements and Bench Test Methods" test standard,a test plan for variable damping shock absorbers was formulated,and specific tests were carried out on the MTS849 shock absorber test bench to obtain the reduction Vibrator speed characteristic curve and indicator characteristic curve;through comparative analysis of the dynamic characteristiccurve obtained by the test and simulation,it is found that their maximum relative error is10.95%,and the error values are within the tolerance of the shock absorber test,and The dynamic characteristic curves obtained from the test and simulation are not distorted,which verifies that the simulation model is established correctly and shows that the design scheme of the damper damping adjustment mechanism is feasible.Finally,in order to further improve the performance of the shock absorber to modify its structural parameters;use Isight and MATLAB software to sample the relevant parameters such as the thickness of the throttle plate,the diameter of the damper connecting rod,the number of gaps in the throttle plate and calculate the points Set to construct the Kriging approximate model,and use NSGA-II as the optimization algorithm to find the optimal solution,and obtain the optimal structural parameters that meet the target damping force.By constructing the mechanical model of the throttle valve,the valve-controlled variable damping shock absorber was restored and the mathematical model of the compression stroke was constructed.In this way,the shock absorber model was built in the MATLAB/Simulink simulation environment and the dynamic characteristics were simulated Compare and analyze with the test results to evaluate its performance;further use Isight software to optimize the structural parameters of the shock absorber and obtain the optimal structural parameters to ensure that the performance of the shock absorber is better. |
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