Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : October 07, 2017 - October 09, 2017
Fiber-reinforced composite materials have been widely applied for their high performance. It is suggested that microscopic physical properties such as fiber-matrix interfacial strength are greatly involved in macroscopic material properties of composite materials. Thus it is expected to apply highly sensitive nondestructive evaluation utilizing contact acoustic nonlinearity to the cylindrical interface. On the other hand, the propagation behavior of harmonic waves generated at the cylindrical interface is expected to be complicated. Hence theoretical interpretation of the higher harmonic generation behavior on a cylindrical interface is indispensable for its theoretical understanding. In this research, the theoretical analysis of the fundamental wave and the second harmonics propagation behavior on a cylinder in an elastic matrix has been carried out. The interface between the cylinder and the matrix is modeled by a spring interface with nonlinear dynamic characteristics and formalized based on the eigenfunction expansion and the perturbation method to analyze the propagation behavior of the fundamental wave and the second harmonics. Furthermore, the frequency response of the forward and back scattered waves of the cylinder was discussed in the light of the resonance phenomenon. As a result, the ratios of stress in forward to backward direction have peaks at the resonance frequencies in both fundamental wave and second harmonics when the interfacial stiffness is relatively large. The second harmonics ratio of stress in forward to backward direction also shows the peaks when either the fundamental wave or the second harmonics satisfy the resonance condition. The magnitude of these peaks strongly depends on the interfacial stiffness of the cylindrical interface.
