The Analysis And Optimization Of NVH Performance For The Vehicle Steering System

As one important system of automobile chassis, the performance of steering systemdirectly influences the smoothness, steering stability and comfort of finished automobile,especially to automobile NVH performance. Abnormal vibration of steering system,especially buffeting of steering wheel, can not only result in a series of problems such asfatigue driving, improper operation and traffic accidents, but also cause the vibration ofrelevant components and parts, accelerate the damage of components and parts, reducethe reliability of automobile, and threaten the driving safety of automobile.Targeting at the existing problems of NVH performance of steering system ofcertain vehicle type at idle operation, this paper adopted the combination method ofsimulation analysis and experimental testing to conduct research on dynamiccharacteristics of automobile steering system. It firstly conducted subjective assessmenton steering system at idle operation; and adopted LMS Test.Lab vibration testing systemto conduct objective vibration test and modal test, so as to acquire vibration spectrum,frequency-weighted acceleration root-mean-square value RMS, vibration total value RSSof frequency-weighted root-mean-square acceleration, and modal parameter. Then, itestablished finite element model of steering system in Hypermesh, and conductedsimulation analysis combining with MSC.Nastran; it verified the correctness of finiteelement model via the comparison between experimental test results and simulationresults. On such basis, it conducted size optimization on part thickness of steering systemvia utilizing finite element sensitivity analysis method and basing on the influence of partthickness to overall quality and various orders of modal frequency sensitivity. Finally, itverified the correctness and feasibility of CAE optimization scheme of steering systemvia subjective assessment, objective test on idling vibration and real car modal testing.Research results show that1-order inherent frequency of steering wheel is close toexcitation frequency of idling engine, generating resonance and causing the shaking ofsteering wheel and substantial decrease of NVH performance of steering system at idleoperation. By optimizing16steering system parts that have big influence to modalfrequency and overall quality,1-order inherent frequency of steering system wasimproved to37.47Hz from28.85Hz, increasing by34.90%; meanwhile, idling operationof steering system was decreased by59.0%than that before optimization.Adopting the combination method of CAE analysis technology and experimentaltest, this paper conducted analysis and optimization on NVH performance of steeringsystem. It has important theoretical significance and practical engineering value to NVHperformance of finished automobile, especially resolving on abnormal vibration ofsteering wheel. Meanwhile, it has important reference significance in improvingindependent R&D level and technical innovation capability of Chinese automobiles.