Comparative study on filament wounded and laminated GFRP composites for tensile characterization

The demand of composite materials has increased tremendously in various industries such as processing industries in making tanks used to process chemicals, in commercial and domestic application such as to LPG cylinders, in automobile industries like in case of car bodies, fuel tanks, aerospace industries, where fuselage wings, landing gears, doors and many other parts of aircraft. The current demand for composites is mainly due to high strength to weight ratio. Hence, we need to understand criticality in the design of composite products. In this paper primarily focused on GFRP for pressure vessels. Hence in this work an initial study was done to compare tensile properties of filament wounded GFRP test coupons with laminated GFRP test coupons which are cut as per ASTM D3039, both these types of samples are fabricated by using glass fiber direct rovings of 2400TEX. Tensile testing samples are prepared by directly cutting test coupons from fabricated vessel and whereas in case of laminated GFRP specimen are cut using hand cutting tool. The obtained results are further compared with analytical results. From comparative study, it is found that there exists considerable difference between experimental and theoretical results for tensile strength and tensile modulus in case of specimens prepared from GFRP pressure vessel. The variation in results is mainly due to presence of void content, poor interfacial bonding between fiber and matrix, fiber fragmentation, improper spacing between fibers, the presence of all these possible defects are justified by fractography study of failed samples in a scanning electron microscope. Hence from fractography study it is clearly justified that why there is least percentage error in tensile properties of laminated composites.