A study on modal characteristics of a commercial vehicle rear door

Abstract

The interior noise level has been an important design criterion lately in automotive industry. Most of the interior noise is generated by the vibrating parts of the vehicle body, mainly the doors. The vibration characteristics of the door panels are affected by the weatherstrip seals. The weatherstrip seals exhibit nonlinear behavior with changing frequency, compression amplitude, temperature and previous load history. These types of materials are very difficult to model and their effect must be studied experimentally. In the anticipation of these needs, we built a modal analysis testing system for determining the dynamic properties of a rear door of a commercial vehicle. Two different configurations are used to perform the experiments. In the first configuration, the door is hung from a supporting frame with elastic cords to simulate the free-free boundary conditions. In the second configuration, doors are mounted to the vehicle body that is supported by air springs. Frequency shifts and damping contribution of weatherstrip seals on the door is investigated by performing experiments with and without the seal using the second configuration. Additionally, having two different configurations for the same structure makes it possible to determine the effect of the boundary conditions on the dynamics of the rear door.