Study On Nvh Characteristics Of Shock Absorber

Shock absorber is an important component of vehicle to alleviate the unevenpavement impact. But, in recent years, because of the universal application of the twintube hydraulic shock absorber existence of unknown noise and harmful vibration, thatseriously affected the quality of the vehicle. Shock absorber NVH is use for studyingthe production and control noise and vibration of shock absorber.Firstly, this paper based on fluid mechanics knowledge to establish hydraulic fluidmechanics model with damper structure parameters and fluid parameters, and providesthe theory basis for the analysis of internal noise damper.Secondly, shock absorber noise is divided into the cavitations noise, vibration noise,outer characteristic distortion noise, friction noise and low cryogenic noise, and focusedon the analysis of cavitations noise and cryogenic noise: On the study of cavitationsnoise, based on the Bernoulli equation theory, established the mathematical model ofcavitations parameters, it have throttle aperture parameter and the oil kinematicviscosity parameter, through analysis found that increasing throttle aperture and dropthe oil viscosity can reduce the cavitations coefficient and drop cavitations noise;Through analysis of the experimental data of low temperature, based on fluid mechanicsmodel, the relationship of the shock absorber damping force and temperature isestablished. It is found that reduce viscosity of oil in low temperature environment ofthe cryogenic noise; Based on theoretical analysis, reducing the tire stiffness,optimization of flow valve and the compensation valve size and improve the oilcompensation efficiency, can reduce the vibration noise, friction noise and outercharacteristic distortion noise.Finally, basing on the modal analysis theory, the three degree of freedom dynamicmodel of suspension system was established. The vehicle body vertical acceleration,suspension dynamic deflection, wheel relative dynamic load and their frequencyresponse function expressions were established. Through establishing the SIMULINKmodel and simulating it found that increasing the shock absorber damping coefficientcan get better ride comfort, and reducing suspension stiffness can reduce resonancefrequency and wheel relative dynamic load, and improving vehicle ride comfort.