Performance of Novel Composites and Sandwich Structures Under Blast Loading
The current chapter focuses on the experimental observations of the resistance of different composite material systems to air blast loadings. These material systems include traditional two dimensional (2D) woven laminated composites, layered composites and sandwich composite materials. A controlled blast loading of pre-defined pressure magnitude and rise time were obtained using a shock tube apparatus. Rectangular plate elements of the desired material system were subjected to such a controlled blast loading and the effect of the blast loading on these elements were studied using optical and residual strength measurements. A high speed imaging technique was utilized to study the damage modes and mechanisms in real time. It was observed that layering of a conventional composite material with a soft visco-elastic polymer provided better blast resistance and sandwiching the polymer greatly enhanced its survivability under extreme air blast conditions. Aside from layering the conventional composite material with a soft visco-elastic polymer, it was observed that layering or grading the core can successfully mitigate the impact damage and thus improve the overall blast resistance as well. In addition to these, three dimensional (3D) woven skin and core reinforcements were introduced in the conventional sandwich composites and their effects on the blast resistance were studied experimentally. It was observed that these reinforcements also enhance the blast resistance of conventional sandwich composites by changing the mechanism of failure initiation and propagation in these sandwich structures. The energies during the blast loading process were estimated to illustrate the energy absorption and energy redistribution properties of the composite panels. The effect of pre-existing impact damage on the failure mechanisms in sandwich structures was also studied.
KeywordsShock Tube Blast Wave Face Sheet Blast Resistance Vinyl Ester
The authors kindly acknowledge the financial support and encouragement provided by Dr. Yapa Rajapakse, under Office of Naval Research Grant No. N00014-04-1-0268. The authors acknowledge the support provided by the Department of Homeland Security (DHS) under Cooperative Agreement No. 2008-ST-061-ED0002:The authors thank Dr. Alex Bog-danovich of 3TEX Inc, for several inputs and discussions during the preparation of the manuscripts on 3D composites. The authors acknowledge Dr. Kunigal Shivakumar of NC A&T University, Materials Science Corporation, and Martin Marietta Composites for supplying composites and sandwich materials used in this study. Authors also thank Dr. Stephen Nolet and TPI Composites for providing the facility for creating the stepwise graded sandwich composites used in the study.
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