Research On Robust Vibration Control Of Car Body Sheet Structure Based On Active Constrained Layer Damping

Coincident with the development of lightweight automobile body has been the decreasing of thickness of body panel and panel stiffness, resulting in the body panel is easy to be excited by the external disturbance and produce strong vibration.And the Vibration mostly focus on low frequency,which seriously affect the NVH performance of vehicle. Active Constrained Layer Damping(ACLD) vibration control technology,combination of the advantages of both passive and active control technology, can maintain high damping characteristic in a wide frequency range, especially excellent control effect in the lower frequency, providing new solutions for the NVH problems of automobile.In this paper, a typical thin-walled plate—the clamped-clamped plate was studied as the object,in order to research active vibration control of plate structure with Active Constrained Layer Damping technology. Firstly, ACLD coupling dynamics model was established with finite-element method with considerision of viscoelastic material with the damping characteristics depicted by ADF(Anelastic Displacement Fields) damping model.Secondly, An optimizing criterion of controllability and observability based on modal H2 norm was adopted, to optimize the piezoelectric actuators and sensors locations, and the feasibility of this method is verified by the example of cantilever plate.Furthermore the modal experiment of the clamped-clamped plate with partially covered ACLD structure which was optimized by the same criterion, is carried out to verify the correctness of the theoretical model. Then, a joint reduction method was presented to address high degrees of freedom of coupling system dynamics model,and to meet the requirements of decoupling property of the control model which was used for the analysis of robust stability problem caused by model parameter error. Complex modal reduction was firstly performed in the space of state,and Modal Hankel Singular Value reduction method was adopted,then a low dimensional model is obtained. On this basis, the model error of the ACLD plate structure was described as structural model uncertainty according to the structured singular value theory,and a robust ? synthesis controller was designed to solve the mixed uncertainty problem of ACLD plate,including modal parameter error uncertainty and unmodeled dynamics uncertainty. Further research on the robust stability and control performance were studied compared with H? controller designed based on traditional small gain theorem. Finally, active vibration control experiment was carried out under different external disturbance excitation.Using the position optimization criterion, the position of actuator and sensor was optimized with parallel consideration of all modes within frequency range of interest, which ensured good controllability and observability of the control system.Furthermore, the control model obtained by the joint reduction has high controllability and observability and good decoupling property,which can be directly used in the design of the ? synthesis controller based on the theory of structure singular value.And the simulation analysis has shown that the closed loop system with ? synthesis controller displayed good robust stability and control effect. Finally,experiments of hardware-in-loop were carried out under different external disturbance excitations, achieving certain degree of control effect. Under four single frequency harmonic signal excitation,the vibration response amplitude decreased 24% ? 54% ? 39% ? 20% respectively after control. Equally, the vibration response amplitude reduced 30% under complicated periodic signal excitation,and the root mean square values of vibration response diminished 9.1% under bandwidth limited gauss white noise excitation.