Topological Optimization Of Viscoelastic Constrained Damping Structure And The Application In The Car Body

The vehicle NVH performance can not only influence the ride comfort,but also is the decisive factor of the automobile brand in the market;as the automotive lightweight target rising,how to take into account the lightweight design when improving the vehicle damping and noise reduction has become an important topic in automobile design.The damping treatment of the thin-walled body panels can effectively improve vehicle interior noise.The viscoelastic damping material is currently widely used on the body.There are many researches on the dynamic mechanical properties of viscoelastic materials and the damping of damping structures.However,there are several points worthy of studying about the damping structure and its application in the car body: finite element modeling of constrained damping structures considering the temperature-frequency characteristics of viscoelastic materials;topology optimization of constrained damping structures based on temperature-frequency characteristics;applications of viscoelastic materials in body structures and related lightweight designs.In this paper,the constraine d damping structure was taking as the research object.The main research contents are:Based on the mechanical properties of viscoelastic materials,the damping characteristics of the viscoelastic material specimens were tested.And the relevant material characteristic curves were drawn according to the test results.Then,the relevant mathematical models were established by the parameter fitting and derivation.The modeling process of the constrained damping structure using the modal strain energy method in the integrated software Isight.Comparison and analysis of the frequency response function(FRF)between the viscoelastic material constant model and the variable model were realized;then,the constrained damping structure topology optimization analysis is carried out by using bi-directional evolutionary structural optimization(BESO)algorithm.The topology optimization study of the structure shows that the temperature-frequency characteristics of the viscoelastic material will affect the precision modeling of the constrained damping structure,and the optimization of the damping material layout can effectively improve the utilization rate of the damping material.The acoustic-structure coupling finite element model of a certain type of vehicle is established.By analyzing the frequency response of sound pressure,it is found that when the white noise of the right zigzag direction of the engine is excited,the sound pressure at the right ear of the driver is higher at 101 Hz.By analyzing the contribution of the body panels,it is determined that the dash panel is to be damped.Through comparative analysis,this measure can improve the interior noise.The mathematical model for the optimization of the damping material and the corresponding constrained layer material in the constrained damping structure was established.The BESO method was used to obtain the material layout of the damping material and the corresponding constrained layer material.In the case of a 40% reduction in the amount of damping material,under the above conditions,the peak sound pressure at the right ear of the driver is almost the same as that of the full layout.In this paper,the constrained damping structure was taking as the research object.The finite element simulation and structural topology optimization of the constrained damping structure were carried on based on the temperature-frequency characteristics of the viscoelastic material.The topology optimization of the constrained damping structure in the body were carried out to ensure the body NVH performance,at the same time,the efficiency of the damping materials was improving.