Research On Bonding Performance Of Coating Forming Luxurious Car Interior Parts

In order to meet the development trend of automobile lightweight and the needs of consumers,the material selection,structural design and manufacturing process of automobile interior trim need to be continuously optimized.Bonding technology,as the main connection mode of coating structure of the automobile interior trim,not only ensures light weight,but also has high strength,uniform stress distribution and great fatigue resistance.However,bonding technology is a relatively complex process,involving many disciplines such as physics and chemistry.Bonded joint is usually a weak link in mechanical structure.Debonding and delamination is a common failure form of multiphase polymer materials or composite bonded structures such as automotive interior trim including dash panel,which will not only affect the transmission and distribution of stress,but also may produce macro cracks in the weak bonded area under the action of external force,Then the damage of the bonded structure may expand,which may eventually lead to the failure of the whole bonded structure.It is very necessary to improve the performance of bonded joint and then improve the strength and stiffness of automotive interior trim.In this paper,the finite element model of bonded structure of car dash panel is established by using ABAQUS software.By obtaining material parameters of the joint,reasonably selecting the element type and setting the boundary conditions,the damage and failure process of surface joint under different displacement loading conditions are numerically simulated based on the cohesive model(CZM).The effectiveness of CZM method is verified by the experiment and another numerical method.The load-displacement curve,the stress nephogram and the damage nephogram of the adhesive layer at a specific time are obtained.We can observe the dynamic process of bonded joint involving damage initiation,damage evolution and failure.The effects of cohesive parameters of the adhesive layer,material and thickness of bonded joint on bonding strength and failure mode are explored,and the mesh size sensitivity analysis of the finite element model is carried out.As the medium of transferring load,adhesive is the key factor affecting the bonding performance.The real dominant factor of the influence of the adhesive type on the bonding strength is the cohesive parameter,that is,the cohesive strength and fracture energy.Based on the widely used description method,Traction-Separation Law,this paper uses the common bilinear cohesive constitutive model.By changing the cohesive strengthσ_cand fracture energy G_C,the effects of cohesive parameters on the bonding strength of the automotive dash panel under Z-direction displacement load and Y-direction displacement load are studied respectively,and the peeling strength and the shear strength of bonded joints are co MPared laterally.In order to obtain high-quality joints,we should not only consider the choice of adhesive,the adherend is an important consideration to be considered.The material properties of the adherend,the geometric dimensions of the joint,such as the thickness,lap length and width,and the thickness of the adhesive layer may also have an i MPact on the performance of the bonded joint.By controlling variables,this paper explores the relatively weak interlaminar position in the three-layer coating structure of car dash panel,and evaluates the influence of the thickness of bonded joint on the bonding strength.