Study On Damping Properties Of Fiber Reinforced Composite

Damping is an important capacity which refers to the energy dissipation of material and system. The application of damping materials is an effective approach to reduce vibration and noise. Fiber-reinforced composites are greatly used as alternatives to conventional materials primarily because of their combination of the superiority properties such as high specific strength, low density, chemical resistance and tailorable properties. However, the research on fiber-reinforced composites mainly focus on the mechanical performance rather than damping property,which largely restrict the development of composite materials. Therefore,the present work embarks from the influential factors of damping performance of composite materials. The factors studied here with regard to different aspects including interfacial strength,the performance of matrix and the composite structure.The factor of epoxy resin matrix was investigated. The influence of matrix resin curing ratio on damping performance of composites was studied through changing the resin-hardener ratio. The results from cantilever beam test show that when the dosage of resin and curing agent is equal or close, the mechanical property is excellent while the damping property is not ideal. The bisphenol A, bisphenol F, hydrogenated bisphenol A and comprehensive epoxy resin was adopted to study the influence of epoxy value, main chain flexibility, lateral flexibility on the damping performance of composites. The results show that the damping temperature range of composites is obviously affected by the corresponding matrix resin. The peak temperature of the damping ratio goes high along with the matrix epoxy value. The main and side chain flexibility of matrix resin influence the damping performance of the composites differently under different temperature.It was studied how the interfacial strength influences the damping properties of the composites. To obtain composites with different interfacial properties, the surfaces of polyacrylonitrile-based (PAN-based) carbon fibers were grafted with polyamide (PAM) and polyamide-ethyl acrylate (PAM/EA) respectively,using the method of "grafting from". Then,use the fibers and resin to prepare fiber-reinforced composites. Scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy (XPS) were performed to investigate the surface morphologies and the surface chemical content of carbon fibers. Interfacial shear strength test (IFSS) and interlaminar shear strength test (ILSS ) were used to characterize the interfacial interaction between fiber and epoxy resin matrix. The results show that the interfacial strength significantly enhanced after grafted. As the interfacial strength enhances the damping peak reduces, and the damping temperature span get wider.The factor of composite structure was investigated using experiment method. The work presents analysis of the damping properties of fiber-reinforced composite with different fiber orientations, plies, areal density and stacking density. With the increase of the creeping angle,the first three mode natural frequency goes down while the forth mode natural frequency magnifies. The second and third mode damping ratio increase first and forth mode damping ratio increase until it reaches 20°. Natural frequency is roughly proportional to the plies, while damping ratio decreases with the increase of the plies. As the areal density increases, the first two mode damping ratio and all the natural frequency reduces. The third and the forth mode damping ratio increases until it attained to 400g/m2 and then decreases. Under atmospheric pressure, the natural frequency are obviously higher. As the curing pressure increases, both the natural frequency and damping ratio reduces.