Quality assessment of class fibre composites by acousto ultrasonic technique

Abstract

This paper deals with the application of Acousto ultrasonic (A-U) technique for quality assessment of fabricated Glass Fibre Reinforced plastic (GRP) composite specimens. GRP composites are becoming the material of choice in many applications. The need for stiffness and strength combined with low density has led the designers of air crafts, missiles, cars, sports equipments and prosthetic devices to turn to composites for most of the components. It has been established that the mechanical properties of any composite materials are generally determined by the properties of fibres. The properties in any direction will be governed mainly by the amount of fibres in that direction. Thus in case of composites the properties may vary from one part to another and it is very difficult to control the amount of defects. The mechanical properties of these composites were widely studied using A-U technique. This technique is essentially an amalgamation of two separate existing technique viz acoustic emission and ultrasonic technique. Unlike the acoustic emission technique this technique is truly non-destructive. only the application of low intensive pulses have to be made and that also for a few second to get a proper evaluation of the specimen. The objective in A-U technique is to simulate stress waves that resemble acoustic emission waves but without disrupting the material. In order to fulfil these objectives, cross ply (0/90) GRP composites were tested by A-U technique, a parameter Stress Wave Factor (SWF) was evaluated and correlated with the mechanical strength (tensile&Flexural strength) of fabricated GRP composites for assessment of quality of these composite specimens.