抄録
In order to solvc the eigenvalue problem of an elastic body with complicated boundaries, a mass system of framework is employed, and the continuous medium is simulated thereby. For the mass system there is no difficulty in satisfying the boundary condition, which is a crucible for a continuous medium. In this way the disturbances caused by the initial excitation in a rectangular elastic body is calculated as a function of time using the finite difference formula, By the Fourier analysis of these propagating disturbances, which is a method with which the free oscillation of the earth is obtained, the eigenfrequencies and the eigenfunctions are calculated for a rectangular body. By this scheme the eigenvalue problem of a finite elastic material is solved. The problem with a crack inside is also solved and the features of spectra are compared with the case without a crack. This kind of technique might be of some use for the non-destructive testing of an elastic material.
