Research Of Bolt Group Assembly Process On The Body-in-White Door

With the continuous development of automotive technology,the quality of the car's body now has become one of the important indicators system to measure performance,the quality of the car's body directly decides the value of the car and its markets.Bolt connection is one of the most important assembly method in mechanical manufacturing.It has the characteristics of simple operation,quick and easy demolition,low cost and high strength load.It is applied widely for the mass production of automobile assembly line and has now become the main assembly method of body-in-white assembly process.The fastening of the bolt connection especially in the key components directly affects the assembly quality and the performance of the whole vehicle which will cause the change of the stress distribution and the fatigue strength of the connected part,resulting in the difference of the bending deformation of the coupling component.Under different conditions,the bolts and the connected parts will be subjected to different loads,and there are different bolt assembly processes for different parts.Therefore,it is difficult to obtain the concrete strength,stiffness and state in various modes of the bolts and the connected parts with the deformation.In recent years,the CAE based on finite element technology has been widely used and practiced in the field of analyzing and designing structure of cars,including vibration,noise,fatigue analysis and analysis of stiffness,strength and stress-strain.However,there are few researches on the influence of the assembly quality of body-in-white door caused by bolt assembly processes,and the study on the impact of different orders and load times of bolt connection on door deformation and stress distribution is not enough.In order to analyze the influence on stress and deformation caused by different bolt assembly processes,pre-tightening force and the order of the force,creating the connecting structure of white body door and the bolt group,the finite element model of four different types of eight-bolt model is created and analyzed by ANSYS to investigate the fluence on deformation and stress distribution caused by different orders and load times of bolt connection on the body-in-white door.By analyzing the simulation results,the best bolt assembly process of body-in-white door is obtained.The results show that for different types of bolt groups with the increase of loading times,the deformation and stress distribution of the outer plate of the door are more even,the mutual elastic effect of the bolts becomes stronger and stronger,and the influence on the deformation and stress distribution of the door is more obviously.On the other hand,the symmetrical loading can improve the uniformity of displacement deformation and stress distribution than the sequential loading.The results of this study can be applied in automobile production process and guide the arrangement.