Ballistic impact efficiency of polymer composites F. Findik * , N. Tarim Department of Materials Technology, Technical Education Faculty, Sakarya University, 54090 Esentepe, Adapazari, Turkey Abstract The use of polymer-based composite materials in the aircraft and automotive industries has been rapidly increasing. In the impact efficiency of some polymer-based composites is experimentally studied. This involved the manufacture of a qu thermosetting resin composite specimens using the hand lay-up process. Subsequently ballistic testing was performed using a se- lection of commonly available firearms with the resulting characteristics experimentally obtained using mechanical and C-scan methods. The results were compared relatively and with previous studies. Eventually the promising advantages for using such materials on an armoured car are emphasized. Ó 2003 Elsevier Science Ltd. All rights reserved. Keywords: Failure analysis; Ballistic test; Mechanical properties; Polymer-based composites 1. Introduction The fibre reinforced composite materials are increas- ingly used in the manufacturing of aerospace and auto- motive structures due to their high strength to weight ratios. Every one of customers wishes good performance and mass production with low cost, but these properties are usually not possible all at once. The aviation industry normally entails components with a high design security without being mainly cost-effective. In the automotive industry the centre of attention is fairly diverse i.e., low cost mass production. The outstanding corrosion resis- tanceof fibre reinforced polymer matrixcomposites makes them predominantly attractive in this latter in- dustry.Previous colleagues [1,2] presentan outline of these products. In the current research, a novellighter armoured car-body manufactured from polymer-based composite materials bonded to an Al-substrate is ex- amined as a substitute to the usual steel product. 2. Experimental procedure 2.1. Materials 2024-T3 Al-substrates are supplied from the ALCOA Company,as rolled form and the thickness of the sub- strateis 0.7 mm. 2024-T3 aluminium being a high strength, solution treated, cold rolled and naturally aged aluminium alloy with 4.5% copper and 1.5% magnesium was chosen due to its higher copper content. Then they are carefully machined in Istanbul Airlines Workshop to the dimensions 200 200 0.7 mm 3 . Glass-fibres prepregs were impregnated by resin using hand lay-up method. In one experimental group; 6, 12, 18, 22, 28 and 36 layersof glassfibresprepregsare produced; and in the second group, Al is bonded to two sides of 6, 12, 18, 22, 28 and 36 layers of glass fibres. The thickness was 0.2 mm per ply. 2.2. Fire tests Al-surfacepreparation and compositeproduction were carried out similar to earlier work [1,2]. Firearm testing was applied to composites with and without Al- substrates. In these tests, nine different guns were used and the speeds of bullets are calculated as in earlier work [5].These testswere carried outin Kayseri Military Airbase in Turkey. The details of guns and bullets are tabulated in Table 1. 2.3. Mechanical tests Tensile testing of the present specimens was carried out using a ZWICK 1474 system. The dimensions of tensile testing specimens used were 80 10 4 mm. The tensile testing speed was set to be 20 mm/min. The * Corresponding author. Tel.: +90-264-346-0269; fax: +90-264-346- 0262. E-mail address: findik@sakarya.edu.tr (F. Findik). 0263-8223/03/$ - see front matter Ó 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0263-8223(03)00065-5 Composite Structures 61 (2003) 187–192 www.elsevier.com/locate/compstruct