Researching the ballistic behaviour of GRP composites produced by different fabrics and different methods

Glass fiber reinforced plastic (GRP) is a composite material produced by molding the glass fiber as reinforcement material and a resin as a matrix together.There are several production methods of GRP composites. The productions could be carried out with simple methods like hand-lay-up and also serial production methods like resin transfer molding. The advantages of GRP against the alternative materials such as, corrosion resistance, low weight, easy assemblying, easy repairing and maintenance properties, makes it preferably used in several fields and the usage of it is being increased by the time.In this research, 0 ? /90 ? oriented-biaxial-glass fiber woven fabrics, 0 ? /90 ? oriented- biaxial-stitched glass fiber fabrics, +45 ? /90 ? /-45 ? oriented-triaxial-stitched glass fiber fabrics and 0 ? /45 ? /-45 ? /90 ? oriented-quadraxial-stitched glass fiber fabrics were used as reinforcing material. Polipol 3401-GRP type general purpose polyester was used as matrix material.The composite productions were achieved by using cold press closed mold method and hand lay-up method with a wooden mold which has a dimension of 600mm 600mm 6mm.40 samples (20mm 20mm) for determining the density, 40 samples (30mm 30mm) for ignition loss, volume and matrix fraction tests, 40 samples (250mm 25mm) for tensile tests, 40 samples (110mm 15mm) for 3-point bending tests and 96 samples (90mm 90mm) for impact tests were prepared so as to determine the properties of composites which were produced by 8 different productions by using cold press closed mold method and hand lay-up method with 0 ? /90 ? oriented-biaxial-glass fiber woven fabrics, 0 ? /90 ? oriented- biaxial-stitched glass fiber fabrics, +45 ? /90 ? /-45 ? oriented-triaxial-stitched glass fiber fabrics and 0 ? /45 ? /-45 ? /90 ? oriented-quadraxial-stitched glass fiber fabrics and Polipol 3401-GRP type general purpose polyester as matrix material, and tests were achieved and macro structures of the composites were analysed.Impact strength is an important parameter to determine the lifetime of the material while designing products but hard to define. Impact test is used to define the strength to impact loads in high velocity and energy absorbed after damaging with impact loads.In this work, impact tests were applied to the glass fiber reinforced and polyester matrix composites produced by four different fabrics (0 ? /90 ? oriented-biaxial-glass fiber woven fabrics, 0 ? /90 ? oriented- biaxial-stitched glass fiber fabrics, +45 ? /90 ? /-45 ? oriented-triaxial-stitched glass fiber fabrics and 0 ? /45 ? /-45 ? /90 ? oriented-quadraxial-stitched glass fiber fabrics) and two different production methods (cold pres in closed mold method and hand lay-up method). Impact tests were achieved by the high velocity impact test machine (Instron Dynatup 9250 HV) at twelve energy levels (25J, 50J, 75J, 100J, 200J, 300J, 400J, 500J, 600J, 700J, 800J and 900J) with an impactor which has a diameter of 16mm and drop weight was 25836g.The damages on composites after the impact tests were analysed with the help of scanning electron microscope and stereo microscope photographs and load-time, energy-time, load-deflection and velocity-energy-time curves from the software (Impulse Acquisition) of the high velocity impact test machine.According to the mechanical and impact test results, the composite produced by cold press in closed mold method with 0 ? /90 ? oriented-biaxial-glass fiber woven fabrics and Polipol 3401-GRP type general purpose polyester, has the best strength values and it was decided that a bulletproof vest could be produced by the same production parameters and the bulletproof vest has been produced.Ballistic shots with Parabellum 9mm calibre bullets were applied to the bulletproof vest produced by cold press in closed mold method with Polipol 3401-GRP type general purpose polyester.The result of the ballistic shots was, the bulletproof vest had no perforation on itself and all the bullets were stopped inside it by the composite material.Key words: GRP composite, ballistics, impact test, glass fiber fabric.