Organizer：State Key Laboratory of Explosion Science and Technology

                    Collaborative Innovation Center of Safety and Protection

Title：         Projectile impact on a fabric-metal assembly –Influence of fabric-metal sequence

Reporter：  Prof.  Victor P.W. SHIM

                    National University of Singapore

Time：        3:00p.m., June 26, 2017

Venue：      Meeting Room, 2nd Floor, State Key Laboratory of Explosion Science and Technology

Biography：

        Victor Shim is a Professor of Mechanical Engineering at the National University of Singapore (NUS). His research interests include dynamic material behaviour, cellular materials, penetration of high-strength fabrics, and projectile impact on protective structures. He established the Impact Mechanics Laboratory at NUS and is an Associate Editor of the International Journal of Impact Engineering. He pursued his Bachelor’s degree at the University of Auckland (1973-76), supported by a scholarship from the New Zealand government, then returned to Singapore to fulfil three years of military service. Thereafter, he was appointed a Senior Tutor at NUS, and concurrently undertook research for his Master’s degree. He proceeded to Cambridge University in 1982 on an NUS scholarship and did his PhD in Impact Mechanics, returning in 1986 to take on an Assistant Professorship at NUS. He has been a Visiting Scientist at the Tokyo Institute of Technology (1989) and a Visiting Scholar at UC San Diego (1996-97). He has received numerous awards for Teaching Excellence and Innovative Teaching, has held several university-level management appointments, and is currently a Vice-Dean of the Engineering Faculty.

Abstract:

        Fabrics woven from high-strength fibres possess a high strength-to-weight ratio and excellent impact resistance. Consequently, they are increasingly employed for protection against projectile impact. In some applications, high-strength fabrics are combined with metallic components to provide sufficient structural rigidity and strength – e.g. for vehicle bodies, aircraft fuselages, building doors, etc. An understanding of how the fabric-metal layer sequence affects the resulting ballistic resistance, is essential for effective design of such fabric-metal assemblies. This motivates the current study, whereby multiple plies (1, 2 or 4) of Twaron (T) aramid fabric were combined with an aluminium alloy (A) plate to form a protective panel. The projectile impact penetration resistance of three types of fabric-metal arrangements were examined – i) the aluminium alloy plate as the impacted face; ii) the Twaron fabric as the impacted layer, and iii) the aluminium alloy plate sandwiched between fabric layers. For assemblies with a smaller number of fabric plies (i.e. 1 or 2), siting the aluminium alloy plate as the rearmost layer results in a higher impact energy absorption capacity, compared to having the aluminium alloy plate as the impacted layer – i.e. for two layers, T/A performs better than A/T. For a three-layer system, the order of impact resistance in order of effectiveness is 2T/A, then T/A/T, then A/2T. However, when the number of fabric plies is increased to 4, a variety of responses was observed. An A/4T configuration absorbs more energy than a 4T/A arrangement, while a symmetrical 2T/A/2T sequence absorbs less energy than either an A/4T or 4T/A configuration. High-speed optical photography images and post-test specimens were analysed, to identify the deformation and failure modes of the fabric-plate targets, and how they are affected by the fabric-metal sequence.