吸音材内部における散逸エネルギーの寄与解析

抄録

In sound-absorbing poro-elastic media, the energy of incident sound wave is dissipated through the following three mechanisms: the viscous dissipation arising the vicinity of the boundary between the solid and fluid phases due to the viscosity of air, the thermal dissipation, and the viscoelastic dissipation due to the damping property of the material used in the solid phase. Contribution of these three dissipated energies are not clear, although the incident energy is considered to be mainly dissipated by the viscous dissipation. In order to evaluate numerically these three dissipated energy separately in the finite element method, one needs to access element matrices, which is generally not easy in commercial softwares. Thus, in the study presented here, we evaluate the dissipated energies by using the analytical solutions for one-dimensional wave equations assuming that the sound is incident normal to the poro-elastic material. Moreover, we analyze the characteristics of the frequency spectrum of the sound-absorbing coefficient by using the relationship between the viscous dissipation and the particle velocity relative to the velocity of the constructed elastic material.