Blast Response of Sandwich Composites: Effect of Core Gradation, Pre-loading, and Temperature
The dynamic behavior of various sandwich composites made of E-glass vinyl-ester facesheets, Corecell™ foam, and polyurea have been studied using a shock tube apparatus. The effects of core gradation, pre-loading, and temperature have been investigated. The overall dimensions of the specimens were held constant, with the only differences arising in the overall thickness of the core. During the shock tube testing, high-speed photography coupled with the nonintrusive optical technique of 3-D DIC was utilized to capture the real-time deformation process, as well as failure mechanisms. Postmortem analysis was carried out to evaluate the overall blast performance of these sandwich composites. Results indicated that (1) increasing the number of monotonically graded core layers reduces the impedance mismatch between successive layers, allowing for a stepwise compression of the core, and thus reduces the strength of the incoming stress wave. (2) The location of the polyurea interlayer has a significant positive effect on the response of composite panels to shock wave loading, both in terms of failure mitigation and energy absorption, if it is placed opposite the blast-receiving side. (3) In-plane compressive loading coupled with the transverse blast loading induces local buckling in the front facesheet, with the amount of damage proportional to the level of compressive loading. (4) The blast performance of sandwich composites at room temperature (22 °C) is superior to its performance at high temperatures (80 °C) and low temperatures (−40 °C).
KeywordsAttenuation Foam Brittle Styrene Photography
The authors kindly acknowledge the financial support provided by Dr. Yapa D. S. Rajapakse, under the Office of Naval Research (ONR) Grant No. N00014-04-1-0268 and N00014-10-1-0662. The authors acknowledge the support provided by the Department of Homeland Security (DHS) under Cooperative Agreement No. 2008-ST-061-ED0002. Authors also thank Gurit SP Technology and Specialty Products Incorporated (SPI) for providing the material, as well as Dr. Stephen Nolet and TPI Composites for providing the facility for creating the composites used in this study.
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