Analysis And Optimization About The Abnormal Noise In The Front Door Of A SUV

As users pay more and more attention to vehicle comfort,abnormal noise has become a major problem in the process of vehicle development.Serious abnormal noises during driving often cause people to feel dizziness,nausea and other discomfort,and thus seriously damage the ride comfort of passengers.Vehicle door is the passageway of vehicle interior space and outer space.It is one of the most frequently used parts of vehicle,and it is also one of the most frequently occurring locationsIn this paper,in this paper,the serious jitter and abnormal noise of the front door interior panel of a certain brand SUV model is presented in the road test.The free mode,vertical stiffness and the stiffness of the corner of the window frame are studied by the method of finite clement simulation and experiment,and the card between the door and the interior plate is discussed.The influence of the thickness,angle and material of the button on its connection performance is obtained,and the optimum design parameters of the buckle are obtained.The main contents and results are as follows:1.The free mode model of front door sheet metal door is established by Hyper Mesh software and MSC.NASTRAN is used to calculate the mode.The mode of vibration frequency below 80Hz is obtained.The first order bending mode is 50.49Hz,and the first order torsion mode is 65.33Hz.The modal test of the front door is carried out through the LMS system,and the experimental value is obtained:the first order bending mode is 52.977Hz,and the first order torsion mode is 67.194Hz.The difference between the experimental value and the simulation value is less than 10%,which verifies the reliability of the simulation.At the same time,both the experimental and simulation values of the free mode meet the requirements of the target.It shows that the mode of the front door has reached the level of the mainstream car design,and the abnormal noise caused by the mode is too weak.2.To analyze the vertical stiffness of the front door sheet metal door,and get the dropping displacement of the weight,200N,400N,600N,800N,1000N,and 1e-5N(unloading),respectively,0.59mm,1.19mm,2.37mm,3.61mm,5.03mm,7.75mm,etc.The experimental control values of vertical stiffness are 0.53mm,1.24mm,2.23mm,3.55mm,4.88mm,7.63mm and 0.34mm respectively.The errors between simulation and experiment are within 10%.When loading for 1000N and 1e-5N(unloading),the target values are less than equal to 8mm and 0.5mm.Both simulation and experimental results meet the requirements.In addition,the deformation of the simulation and experiment on the stiffness of the corner of the window frame is 4.53mm and 4.73mm respectively.The error rate between the simulation and the experiment is only 5%,and it is less than the target value 5.5mm.The vertical stiffness of the door and the stiffness of the window frame meet the level of the mainstream vehicle design,and exclude the fact that the stiffness of the front door is insufficient.3.Using the finite element analysis tools such as Hyper Works and LS-DYNA,this paper simulates and simulates the circular clamping and pulling process of the front door and the inner plate.The insertion force and the retention force of the buckle are 49.4N and 122.4N respectively.In order to verify the accuracy of the simulation,the insertion force and the mean of the retention force are 42.4N and 120.3N respectively,although the insertion force and the average of the retention force are 42.4N and 120.3N respectively,but there are some cutting phenomena in the plucking experiment,and the retention of some groups of clasps is lower than the target value of 120N.As a result,it not only has the problems of unreasonable structural design,and its connection performance can't reach the use requirements of the front door of the SUV,which may be the main cause of the abnormal noise of the front door jitter.4.In view of the unreasonable design of the buckle structure and weak connection performance,the effect of the material,the thickness and the angle of the buckle design parameters on the connection performance is discussed.The optimum selection of the buckle is POM,the thickness of the flap is 1.4mm,and the angle is 150 degrees.The design parameters make the original clamping force increase by 49.1%.The experiment of door vibration shows that the problem of jitter and abnormal sound of interior panel is solved successfully after optimization.