Theoretical And Semi-Empirical Modeling On External Characteristic Of Shock Absorber And Software Development

Theoretical and Semi-Empirical Modeling on External Characteristic of Shock Absorber and Software DevelopmentIn recent years, the demand of automotive parts'quality is increasing with the development of automotive industry.Vehicle shock absorbers play a very important role in vehicle handling, stability and ride performance,which has a key effect on the competitions in automotive industry.However,design tools in the domestic shock absorber plants,which finish the product development by themselves,are still very limited.They use the traditional design method based on physical prototype and testing,which has a long development cycle and high cost.This method can not fulfill the requirement of current automotive parts industry,and a simulation-based design software for shock absorber is necessary.This paper can be elaborated:theoretical study and the applications of the study results.In the part of theoretical study,a theoretical shock absorber model based on physical parameter has been developed.Theoretical model can reflect the effect of changing shock internals.It is also the basis of the shock absorber design software and physical parameters optimization.Theoretical model with too many parameters will take longer to evaluate, which is less suitable for simulation. So semi-empirical shock absorber model with higher accuracy and less parameters has been developed for simulation purposes. Semi-empirical model can be evaluated faster and also reflect the effect of changing physical parameters.This paper also developed a method based on nonlinear least square method to optimize the physical parameters and to determine semi-empirical coefficients.In the part of the applications of the study results mainly developed two software-shock absorber design program and physical parameters optimization/identification program. With shock absorber design program we can easily to know the relationship between external characteristic and physical parameters. Physical parameters optimization/identification program can optimize the physical parameters in order to best suit the target curve.We also can use it to identity the physical parameters without dismantling the shock absorber.The process of the software development is based on comprehensive use of MATLAB,which include MATLAB/Simulink, MATLAB/GUI, lsqcurvefit tool in optimization toolbox, Rapid Simulation Target(rsim) in real time workshop(RTW),M-file compiler and MATLAB compiler. The executable program finally gained can run independent MATLAB environment,so it can be used without MATLAB on the end-user's system.MATLAB Compiler 4 also uses a Component Technology File (CTF) archive to house the deployable package. All M-files are encrypted in the CTF archive using the Advanced Encryption Standard (AES) cryptosystem, where symmetric keys are protected by 1024-bit RSA keys.So it can protect the algorithm of the program.And the program can be released for commercial purpose.