Vibration And Sound Radiation Analysis Of Multi-layer Damping Composite Structures

Viscoelastic damping technology is an important method to reduce the structure vibrationand sound radiation, which has been widely used in modern industrial fields. With theimprovement of the engineering requirements and the development of vibration reductiondamping technology, multilayer damping composite structures get more and more attentionsand applications gradually. Due to the particularity of multilayer damping compositestructures, it is difficult for the traditional finite element model to describe the mechanicalbehavior. Besides, there are few systematic researches on the vibration and sound radiationcharacteristics of damping composite structures. Focused on the multilayer dampingcomposite structures, the vibration and sound radiation characteristics are analyzed by Finiteelement and acoustic boundary element methods. The major research works are as follows:(1) The materials of multilayer composite structures are discontinuous along the thickness.The shear deformations and thicknesses of each layer are not consistent. Considering thesecharacteristics, a new laminated shell element construction method is developed. Based onlayerwise theory, the displacement modes of each layer are described by interpolating thedisplacements hierarchically and linearly. The displacement fields of each layer aredetermined according to Timoshenko beam theory and generalized conforming method. Theelement can describe the mechanical properties of the laminated structure accurately, andcalculate each layer deformation of the laminated structure with thick and thin layerscoexisting with high accuracy. It can reflect the deformation features of laminated structuresactually.(2) By using this laminated shell element, the finite element dynamic analysis model ofmultilayer damping composite structures is established and verified. Single and two layereddamping composite structures are analyzed by using factorial design methods to find out thedamping material parameters influences on validation characteristics of the compositestructures. Some conclusions which are helpful for anti-vibration design are summarized. Theeffectiveness and universality of conclusions are demonstrated by the validation analysis ofthree layered damping composite structure.(3) Based on the dynamic response of structure finite element analysis, the soundradiation of damping composite structures is calculated by acoustic boundary element method.With sound radiation analysis of two and three layered damping composite structures, theinfluences of damping layers’ elastic modulus, density, damping loss factor and laid order onthe radiated sound power are discussed.(4) In order to facilitate applying the calculation and analysis method in practicalengineering problems, a software tool to calculate dynamics of multilayer damping compositestructures is developed based on object-oriented programming method. In this way, theapplication of vibration and noise reduction technology with multilayer damping compositestructures could be more convenient.