ASA 127th Meeting M.I.T. 1994 June 6-10

2aPA13. The dynamic response of a window embedded in a 3-D structure to sonic boom overpressures.

Kyle Martini

Joel Garrelick

Cambridge Acoust. Assoc., Inc., 200 Boston Ave., Ste. 2500, Medford, MA 02155-4243

Ground level sonic boom overpressures are often in the linear acoustic regime, allowing structural damage assessments to be performed using structural acoustic techniques. In this talk the boom-induced dynamic response and stress of a glass window is computed. The window, modeled as an elastic thin plate, is embedded in an enclosure that may also be elastic. Solutions are obtained numerically using nashua, a general purpose finite element/boundary element computer code. Peak response/stress is calculated as a function of the relative orientation of the incident wave in azimuth and elevation, the former determined by the flight path and the latter by the Mach number. For a given boom spectrum level, the peak response probability density function (PDF) is calculated assuming a uniform probability of flight direction. By invoking structural acoustic reciprocity, this is related to the directivity of the pressure radiated by a force applied to the window at the peak response location. Finally, the effects of enclosure baffling on the surface pressure itself is presented and compared with free field and infinite baffle approximations. [Work sponsored by Armstrong Laboratory, WPAFB, U.S. Air Force.]