Investigation on Flexural Response of GFRP Composite Laminate Subjected to Low Velocity Cyclic Loading

The suspension systems in automobiles are to provide adequate flexure modulus and damping in response to the road tyre interaction. This will ensure adequate driving comfort. In this context, as a weight reduction measure and to provide sufficient response to the vehicle dynamics leaf springs made of composite materials and can be a replacement for traditional metal leaf springs. Hence the present study on the GFRP composite laminate is to experimentally simulate the loading environment in the vehicle and the response of spring leaf made of composite material. GFRP composite laminate specimen of configurations such as Unidirectional Laminate (UD-0), angle ply laminate (0/30/60/0 and 0/45/0/-45) and symmetric and non-symmetric cross ply laminates (0/90/90/0 and 0/90/0/90) are prepared by hand lay-up technique. The laminates are exposed to low cycle (4.6 Hz and 8.6 Hz), constant amplitude cyclic loading in the laboratory setup. The flexural modulus of the virgin and pre-cyclic loaded specimen is measured by three point bend test using digital UTM as per ASTM D 790. The flexural modulus of the pre-cyclic loaded laminate specimen presents a positive improvement up to certain loading cycles at low frequency (4.6Hz). At high frequency (8.6 Hz) loading cycles there existdegradation in the flexural modulus of the pre-cyclic loaded specimen. The enhancement and degradation of flexural modulus on exposure to cyclic loading signify the influence of loading cycle frequency and laminate configuration. Any variation in the specimen configuration apart from UD-0 ply, record a drop in the flexural modulus. The optimum flexural responses characteristics in composite material are attributed to the selection of lay-up configuration and loading condition.