CAE Analysis Of Nonlinear Squeak And Rattle In Automotive Instrument Panel

As one of the main problems that affect customer’s satisfaction in the automobile design,squeak and rattle have strong nonlinearity,of which the principle and characteristics are very complicated.The instrument panel is the most visible position in the interior parts,and its components have a large number of surfaces in contact with each other,so most squeak and rattle come from the instrument panel.During the working life of a car,it will experience different temperature conditions such as low temperature,normal temperature and high temperature,so it is necessary to study the squeak and rattle performance of the instrument panel at different temperature.Most of the parts on the instrument panel are made of plastic materials,mainly include PP+EPDM＿T20,PP＿T20,PC/ABS and HDPE.The electronic universal testing machine was used to conduct quasi-static tensile test on the main materials of the instrument panel,and the digital image correlation(DIC)method was used to obtain the elastic modulus and Poisson’s ratio of the materials at the temperature of-30℃,10℃,23℃ and 50℃,so as to provide material parameters for the finite element modeling of the instrument panel.The principles of the Ziegler SSP-04 material compatibility testing machine was researched,and the squeak and rattle risk priority number(RPN)and the impulse rate during the stick-slip of PC/ABS and coated material PVC in-30℃,10℃,23℃ and 50℃ were measured.Then range of the relative displacement caused by a single pulse at different temperature was acquired,which provides a reference basis for the analysis of the squeak of the instrument panel.The evaluation principle of squeak and rattle was analyzed.Then according to the material parameters,the preprocessing was carried out on the instrument panel.And the relative displacement of adjacent components under the road excitation was calculated with transient response analysis by using Optistruct.According to the relative displacement of the single impulse and the designed gap between two adjacent components,the risks of squeak and rattle at different temperature were identified.The results show that the higher the temperature,the greater the maximum relative displacement between adjacent components,and the greater the risk of squeak and rattle.In the later stage of the test,according to road signals collected by the sample vehicle on the special road surface for squeak and rattle,the vehicle four-columns test was conducted at low temperature,normal temperature and high temperature environment in the laboratory,and the instrument panel was tested on the vibration table,so as to check the squeak and rattle problem in the instrument panel and make suggestions for rectification.The acceleration sensors were used to measure the relative displacement of the boundary position of the instrument panel at room temperature.Compared the value of simulation and experience,the two trends are basically consistent,indicating that the simulation model is effective and reliable.The simulation method can be used to analyze the squeak and rattle of vehicle components in the early design stage.