Structure Parameter Optimization Of Amplitude-selective-damping Shock Absorber Based On Ride Comfort

The demands for different performance of vehicle often are incompatible：Improving ridecomfort and reducing the vibration of the sprung mass require the lower damping force ofsuspension system. Reducing tire dynamic load and suspension dynamic displacementrequire the higher one. Take Handling stability of a full vehicle into consideration, In orderto reduce the angle of dip of body and response time when the vehicle is turning, thesuspension should be harder. Matching vehicle suspension damping is a tradeoff thatgenerally take all aspects of the vehicle with different performances into account.At present, ordinary hydraulic shock absorber has been widely used in the automotivesuspension, but the damping force of the general dampers depends only on the relativevelocity between the vehicle body and the wheels. The damping characteristics of shockabsorber is relatively fixed and it will not make corresponding changes to the conditions ofthe vehicle. It is difficult to reconcile the contradictions between different performances ofvehicle, such as handling stability, ride comfort and driving safety, which cannot make theperformance of vehicle optimal in different working conditions.With the continuous advances in automotive technology, as one of the new subjectsdeveloped in recent years, active suspension technology can make sure that the suspensionwoks in the best conditions via timely adjust suspension stiffness and damping according tothe movement parameters of the automobile and the road surface, it is also in the bestdamping state. However, the complex test devices, energy sources, actuators and controlprocessors need to be installed on the vehicle. Compared with ordinary passive suspension, itis high cost, poor reliability and difficult to scale popularization and application.This paper proposes an amplitude-selective-damping shock absorber whose dampingcharacteristic can make corresponding changes to the amplitude of suspension movement.When the vehicle is traveling on a good road, the shock absorber may provide little dampingto ensure good comfort; when the vehicle is turning or driving on bumpy roads, this shockabsorber can provide greater damping to ensure good handling stability and driving safety.By distinguishing different vehicle driving conditions, the damper can provide different damping characteristics. In this way, this kind of shock absorber can solve the contradictionbetween the different performances of the vehicle’s suspension damping demand.By attaching the cavity and floating piston in the piston rod, the dampingcharacteristics of the amplitude-selective-damping shock absorber can change with theamplitude of amplitude of vibration automatically without the need to install sensors andcontrol systems. This type of shock absorber can be adapted from the structure of generaldamper easily. It is with the simple structure and low cost and it is suitable not only forsimple suspension modifications to the individual enthusiasts but also for enterprises toquantify the production and obtain good value for money.This article aims to optimize the structure parameter of amplitude-selective-dampingshock absorber based on ride comfort and the main work of this paper is divided into fourareas:First, establish the theoretical model of the original shock absorber used in the car andcompare with the result of dynamometer performance test and speed characteristic test onthe damper test bench. With the foundation of establishment of the theoretical model ofamplitude-selective-damping shock absorber, establish an AMEsim equivalent hydraulicmodel based on the actual structure of the damper.Secondly, in order to study the ride comfort of the vehicle, establishing a model ofvertical vibration based on theoretical models.Again, minimum of the sum of the weighed acceleration RMS (Root Mean Square)multiplied by the proportion of working conditions was considered as the target function ofoptimization, select the shock absorber structure parameters as optimization variables andgive the range of the variables. In order to ensure handling stability and driving safety, tirerelative dynamic load and suspension deflection must be within a certain range. In this way,we can establish the optimal model based on vehicle ride comfort. Finally, make use of data processing capabilities of MATLAB, multi-island geneticalgorithm of iSIGHT to optimize the parameters of structure of damper.And then, we set theresults into the vehicle vibration model and compare with the original shock absorber toverify the improvement effect of amplitude-selective-damping shock absorber in the field ofride comfort.