Composite Plate Response to Shock Wave Loading

Abstract

The mechanical response and characterization of composite materials under transient dynamic loading caused by shock or blast wave impingement is not well understood. Air blast is associated with a fast-traveling, high-pressure shock front followed by a lower pressure expansion wave. The timescales associated with the shock front are typically 103 faster than those associated with the expansion waves which follow. A new split-view Time-Resolved Stereo Digital Image Correlation system has been developed capable of measuring time dependent information of three component displacement vectors on two dimensional surfaces in a shock tube facility where transient aerodynamic loads on material specimens develop over the short time associated with the shock wave reflection time scales. To validate the techniques we embedded strain gauges in a S-2 glass epoxy 12.7 mm thick composite test specimen during in-house using vacuum assisted resin transfer molding fabrication. High-frequency-response, semiconductor, strain gauges were used in various combinations and locations in order to measure the transient strain rate during the impingement of the shock wave. In addition to strain gauges PZT transducers were also embedded which helped measure the frequency response of the test plate. In-house fabricated composite plates were tested under three different boundary conditions: clamped, quasi-simply supported, and bolted. Different displacements and deformation patterns were observed in each of these cases.