An analysis of the response of Sooty Tern eggs to sonic boom overpressures

Abstract

It has been hypothesized that sonic booms caused a mass hatching failure of Sooty Terns on the Dry Tortugas, FL by causing eggs to crack. In this paper the problem is analyzed using two levels of idealization. The first model represents the egg shell as a spherical elastic shell, the embryo as an inertial concentric sphere, and the albumen as an acoustic fluid that completely fills the intervening volume. The substrate is taken to provide a point support for the egg and to double the incident pressure. The second higher fidelity, numerical model accounts for the ‘‘egg shape’’ geometry and allows for an air sac. Here the substrate is modeled as a rigid boundary of infinite extent. In both cases the boom is modeled as an incident, planar N wave. Predictions are compared to each other and with the results of empirical studies previously performed by other investigators. Data from these earlier investigations were obtained with boom-like impulsive noise sources and indicate that the hypothesis that sonic booms crack eggs unlikely. [Work sponsored by Armstrong Lab., WPAFB, U.S. Air Force.]