| With the rapid development of automobile industry, consumers have more strictdemand for automobile performance. As a kind of original damping, shock absorber isone of the most important parts of automobile suspended frame, its main function is toaccelerate the attenuation of vibration energy, playing a decisive role in the vehicleride comfort and handling stability. Therefore, the research of designing shockabsorber is an important part of the whole vehicle research. For research on thetraditional shock absorber, how to ensure the matching shock absorber with vehicle,improving the vehicle ride comfort and handling stability is a problem for engineers.As a result, establishing the shock absorber model by computer simulation, simulatingthe shock absorber various features has important significance for improving theefficiency of research and development of shock absorber and in-depth study.In fact, the shock absorber is a complex nonlinear system, the nonlinearcharacteristics is mainly affected by three factors: large deflection of valve slice, theoil temperature change and mixed gas oil compressibility. In recent years, domesticand foreign scholars conducted a lot of research work about shock absorber model,establish all kinds of model. Though these shock absorber model, reflect therelationship between the damper characteristics with the speed in a certain extent, butthere is no related research bringing these factors uniformly embedded into shockabsorber model, analyzing systematically the impact of these factors on the dampercharacteristics, and verifying the precision of model in the simulation of the vehiclecalibration.In view of the above analysis, this article does the research in view of the shockabsorber model, embedding the large deflection of valve slice, oil temperature mechanics and mixed gas oil compressibility into the model, and analyzingsystematically the influence of the three factors on the shock absorber. This workmainly divided into the following three parts:The first part mainly introduces the process about how to establish the physicalmodel of the shock absorber in accordance with large deflection, the order of thethermodynamic model, oil compressibility model of modeling; Firstly, analyzes theworking principle of double cylinder hydraulic shock absorber and simplifies theshock absorber system, based on fluid mechanics theory, establishing the relationshipbetween the flow and pressure of valve system. Perturbation method is used to solveelastic mechanics equation of valve plates, and accuracy is verified by finite elementanalysis, solving the problem of large deflection valve plates, and obtaining therelationship between the flow and pressure after the preloading valve open; Secondly,the paper analyzes the heating principle of shock absorber, basing on the first law ofthermodynamics, deducing the heat conduction model of shock absorber, theconvective heat transfer model, the radiation heat transfer model, establishing oilviscosity-temperature characteristics model of shock absorber and thermodynamicmodel, calculating the thermal equilibrium temperature of the shock absorber, andobtaining the change about shock absorber temperature with time; Finally, the paperanalyses the cause why shock absorber produce bubbles, and summarizes how thebubble effect on shock absorbers. By deriving the relationship between temperature,pressure and gas in the shock absorber, establish the gas mixed oil of compressiblemodel.The second part mainly validate the accuracy of the established physical modelthrough damper test; First of all, by experiment verify the valve plate split valve withlarge deflection characteristics of precision, and the influence of compressibility onoil damper hysteresis characteristics, and study the structure of the valve parameterson the shock absorber of the external characteristic influence; Secondly, thethermodynamic model was verified by means of temperature rise test that caneffectively reflect the phenomenon that shock absorber damping force decrease with the temperature, and study influence that the structure of the valve parameters how toaffect the equilibrium temperature of the shock absorber; Finally, through thehardware in loop test verify the accuracy of the established physical model, providingguidance that how the shock absorber damping characteristics and the performance ofthe vehicle match.The third part optimize the valve structure parameters of the shock absorberbased on the ride comfort, on the basis of the shock absorber of physical model testand the characteristics of impact study. First of all, according to the comfortevaluation index, establish the optimal objective function. Then use themulti-objective genetic optimization algorithm, obtain the expectations curve of shockabsorber needed for vehicle model characteristic and the corresponding structuralparameters; Finally, study how the oil temperature characteristic and oilcompressibility affect the suspension ride comfort through simulation... |
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