Effects of Thermal Shock on Mechanical Behaviour of Kevlar Fibre Composites

Ray, B C and Hassan, S T and Clegg, D W (1998) Effects of Thermal Shock on Mechanical Behaviour of Kevlar Fibre Composites. In: Proceedings of Composite Materials. NML, Jamshedpur, India, Jamshedpur, pp. 214-223.



The development of composite technology represents one of the most significant advances in materials science since 1940s. The major advantages of composite materials are their high strength and stiffness, light weight, corrosion resistance, crack and fatigue resistance and design flexibility as compared to metallic materials. Because of the attractive properties. the use of composite materials has been increasing steadily in recent years. Unfortunately, there are disadvantages in composite materials as compared with metals. They include brittleness, vulnerability to stress concentration, inflexibility for localised multidirectional stresses, sensitivity to environmental effects, and poor damage tolerance to impact. These factors must be critically considered in designing a composite system. The aramid keviar family of fibres have been accepted as reinforcement for composites and finds wider and newer applications in various industrial and aerospace sectors. The interfacial bond strength between aramid fibres and epoxy resins is normally lower than what is experienced with carbon fibre composites. This weakness with kevlar necessitates investigation and evaluation of the interlaminar shear strength (ILSS) and modulus under some realistic environmental conditions. The present work has been taken up to evaluate the variation of ILS S and modulus values after being given the extreme thermal shock of 160°C thermal gradient. The thermal shock is given in two separate ways, firstly, one series of kevlar/ epoxy and kevlar/polyester short beam shear (SBS) specimens are kept in a oven at 80°C for different time intervals and then immersed in a liquid bath at -80`'C temperature. The other experiment is done in reverse way i.e. first kept at -80°C and then exposed to 80°C temperature. The interesting variations of ELSS and modulus values have generated some ideas for assessment in this area. The thermal shock, positive temperature and cryogenic temperature affect the kevlar/epoxy and kevlar/polyester composites in a very complex way. The wide fluctuation in results necessitates further investigation and depth analysis of this interaction, It may be hypothesised that the extreme thermal shock may introduce some decohesion between fibre/matrix interface especially when the gradient is positive in thermal shock.

Item Type:Book or NML Publication
Uncontrolled Keywords:corrosion resistance; reinforcement
Divisions:Material Science and Technology
ID Code:2680
Deposited By:Sahu A K
Deposited On:18 Mar 2011 14:50
Last Modified:06 Jan 2012 11:47
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