Acoustic Approximations in Fluid-Shell Interactions

Acoustic field approximations, valid for short time after initiation of loading, are derived for spherical shells (the plane and spherical wave approximations) and proposed for shells of arbitrary geometry (the plane and the mean-curvature wave approximations). They are used to obtain the transient response of spherical and spheroidal shells to a suddenly applied uniform pressure and the results are compared with exact solutions. The examples investigated show that these approximations can be used to obtain good estimates for the response of the shell. In the case of one of the spherical shells investigated, the plane wave approximation fails while the spherical wave approximation gives a conservative answer.