Study Of Modal Characteristics Of A Car Body-in-White

At present, the automotive industry's competition have bean increased sharply. New models the rate of the new models replacement depends largely on the design of body-in-white. The design of a model often used to go through a few years, while making hundreds of cars need experiment to meet the Request of the design. So it cost so much and have a long design cycle. The design cycle and the sample n of design has been greatly reduced due to we used a number of advanced design. Among the modern designs of cars, computer-assisted technologies greatly improve the efficiency of the design and development. In the process of developing new models, the design of body-in-white has been the dominant design, and the inherent characteristics directly impact on vehicle performance. In order to have good characteristics of vehicles, it generally require body-in-white with a higher body-in-white stiffness and good vibration characteristics. These characteristics are usually obtained through Stiffness analysis.In this paper, taking a concept design phase of body-in-white as the object, we establish a body-in-white finite element model base on the pre-processing software Hypermesh and Finite element method software MSC.Nastran. First of all, based on body structure of body-in-white with spot welding, carbon dioxide gas shielded arc welding (referred to as welding CO2) and other forms of connecting research, we establish body-in-white finite element method model which is able to accurately simulate the performance of the body structural dynamics, calculate the size of a computer acceptable range, and model efficiency based on a shell element.Secondly, through finite element method stiffness analysis, we got body-in-white natural frequency and vibration mode modal parameters. From the vibration and the strength point of view, we analysis the impact of intern and extern of body-in-white.Again, compared to the modal test data of competing products in the vehicle body of body-in-white, we found that the gap between the two modal frequency is larger and larger post-design problems, so to avoid such risks. In this paper, we have a program of the design to provide directional guidance for the design. We take to the body structure of body-in-white with longer, wider and so on to amend the characteristic parameters of the combined surface of model, to ensure that the body-in-white structure is more reasonable model.At last, in accordance with the strain modal characteristics of the locality of strain modal, it is to determine the location of the body structure maximum elastic deformation method and to targeted strengthen the body of the local stiffness.The results show that this method is reasonable and practical for the car body design.