Significance of cyclic loading parameters on the flexural response of the GFRP composites

Abstract

Automotive design calls for weight reduction, considering fuel consumption and vehicle dynamics as well. Application of composite materials for suspensions and other structural members is in that direction. Owing to their high specific strength and inherent structural damping qualities, composites can be an alternative to metallic materials, especially with the suspension-springs. Further, epoxy composites can resist environmental influences, facilitating easier maintenance. In this study, we assessed the flexure response of GFRP composite exposed to pre flexure cyclic loading. This was to simulate the loading environment of an automobile leaf spring. Experiments were conducted with Taguchi’s DOE using L9 orthogonal array with two factors and three levels. The test specimens were prepared by hand lay-up technique with four layers of (0/0/0/0, 0/30/60/0, 0/90/90/0 and 0/45/0/-45) orientation. Constant peak amplitude cyclic loading was imposed on the specimen by an eccentric disc in a radial drilling machine. The flexural modulus of the cyclic loaded specimen was obtained by three point bend test as per ASTM D790. Assessment of the test results by ANOVA, S/N ratio and regression analysis indicated that the flexural modulus of the pre flexural cyclic loaded composite is significantly influenced by the loading parameters (loading cycle and frequency), and the flexural modulus can be enhanced with reduced fiber orientation interactions within the lay-up at critical operating conditions. The damage pattern influenced by fibre orientation in the lay-up sequence is ascertained by SEM images.