BEHAVIOR OF SANDWICH COMPOSITES UNDER FLEXURAL AND FATIGUE LOADING: EFFECT OF VARIATION OF CORE DENSITY

In the present work, the authors have made an attempt to study the flexural and fatigue behavior of Eglass/ Vinyl ester/Polyurethane foam sandwich composites. Three types of sandwich composites were synthesized with E-glass fabric and polyurethane foam densities having 65:35 ratio of fibre to resin weight fraction. The sandwich specimens were prepared by hand lay-up method followed by compression at room temperature. The specimens are then tested mechanically to ensure flexural and fatigue behavior. The objective of the present work is to investigate the integrity of sandwich composites with E-glass reinforcements over the variation of foam density. The effect of different test frequencies such as 1Hz, 3Hz, 5Hz, 7Hz and 9Hz respectively are applied during the test. The experimental study reveals that the cyclic load and test frequency play a critical role in determining fatigue strength and change in core density attributes to the failure through foam-face sheet delamination, and at higher frequencies early stiffness degradation leading to foam crushing and failure dictated by the shear strength of the sandwich composites.