Shock wave impact on monolithic and composite material plates: The preferential aeroelastic response

Abstract

An experimental investigation was carried out to determine the aeroelastic response of thin flat plates during face-on impact with planar shock waves. The experiments were performed in a large-scale shock tube research facility, which had a working section of 12″ in diameter and a length of 80 ft. One aluminum plate, one stainless steal plate and several composite plates were tested in the present investigation. Miniature semi-conductor strain-gauges of high-frequency response were employed to measure locally the strain on the exterior side of the plates and high-frequency response pressure transducers were used to measure time-dependent wall and total pressure. Due to the elastic deformation of the plates and their reverberation, strong acoustic waves were generated on the external side of the impact which carry a significant signature of the plates’ properties. Composite plates were found to suppress several of the modes of the wave patterns while metallic ones demonstrate a rich variety of interacting modes. The amplitude of the excited acoustic waves, however, was higher in the case of composite plates than in the case of steel plates. The frequency content of the strain signals on the surface of composite plates was not always the same with the content of the surface acceleration measured in free vibration experiments. Calculations by using a coupled system of equations between the fluid and solid phases of monolithic materials provided predictions in good agreement with the measured values of modal frequencies. These theoretical results were also in agreement with the classical modal analysis results by using the Poisson–Kirchoff theory for thin plates under axisymmetric or non-axisymmetric conditions.