Design And Analysis Of Lightweight Noise And Vibration Reduction Approaches

With the rapid development of the automobile industry, the vibration and noise control performance becomes more and more critical to end users. In addition, the energy crisis and environmental protection raise new challenges to the automotive industry. It has been shown that reducing the total weight of the vehicle usually leads to better fuel economy, handling stability and the safety. Therefore, lightweight design has become an important task in the modern automobile design process. Damping treatment on the vibration surface and dynamic vibration absorbers are two important measures for vibration reduction. Viscoelastic materials, which have been widely used in many industrial fields, can reduce the structure’s vibration effectively in a wide frequency range. The dynamic vibration absorbers(DVAs) consisting of concentrated mass, springs and damping material are also widely used for vibration and noise reduction because of its flexible design ability. The two methods have their advantages and disadvantages, and they both bring some additional masses to the original structure. In this paper, the vibratoin control effectiveness of damping treatment and dynamic vibration absorbers are compared in terms of the added masses. One goal of this study is to seek lightweight approaches for vibration and noise control of car bodies.The simply supported beam is chosen to investigate the vibration control effectiveness of unconstrained damping layer (ULD), constrained damping layer (CLD) and dynamic vibration absorbers (DVAs). The theoretical model of simply supported beam with unconstrained damping layer is modeled as well as the beam with DVAs attached, then the displacement and velocity of the beam are predicted using the models. Furthermore, a finite element model of beam with constrained damping layer is developed in MSC. NASTRAN, from which the velocity response of the beam is obtained. Next, velocity response of the beam with the constraint damping layer is compared with those of the free damping layer beam and the DVAs beam. Both the analytical and the finite element models are validated experimentally. The vibration reduction abilities of ULD and CLD depend on the parameters of viscoelastic materials which are determined by their manufacturing processes and may not be chosen freely during applications. On the contrary, the DVA parameters can often be easily optimized, presenting much design flexibility in the vibration and noise control of the structure.In this paper, three groups of DVAs are designed. The first design consists of one DVA weighting10g targeting at attenuating the first resonant of the simply supported beam. The second and the third designs consist of three DVAs, each of10g and6g respectively, targeting at attenuating the first three resonances of the beam. The vibration reduction results are compared to that the ULD and CLD, which have added weight of30.8g and18.4g, respectively. It is shown that, the CLD leads to better vibration reduction results than the ULD, and the CLD also has less added weight. The DVA weighting10g has a better vibration control result than the ULD and CLD at the first resonant frequency. And it is found that the ULD attenuates the vibration more effectively at the higher frequency range than at the lower frequency range. In summary, the DVA approach has some advantages than the ULD and CLD approaches for vibration reduction at lower frequencies and at resonant frequencies. Furthermore, as the weight increases, both the control effectiveness and bandwidth are improved for the DVA approach. Overall, if the added masses are the same, the DVA approach is more effective than either the ULD or the CLD approach to suppress the resonances of the simply supported beam.