A Methodology for Enhancing the Shear Response of Sandwich Composite Panel: Sandwich Composite Panel with Stair Keys

Objectives: In composite sandwich panel, delamination between the foam core and face sheet is due to inability to withstand shear load. Hence a methodology of introducing shear keys for enhancing the shear response to resist delamination is analysed in the present study. Methods/Statistical Analysis: The conventional sandwich panel under analysis is composed of Glass Fibre Reinforced Polymer (GFRP) skin with PVC (Polyvinyl chloride) foam core impregnated with epoxy resin. The present study is to introduce stair keys in between GFRP and PVC which are made by overlapping GFRP face sheets, with the length and depth to get the required step size. Parametric Finite Element (FE) investigation using ANSYS software has been performed to evaluate the foam core performance by grooving the foam material as stepped shapes. The effect of different length of the stepped grooves in foam material are analysed and its results are compared with conventional sandwich panel. The stair key response for number of steps ranging from n = 1, 3, 5 and 7 are investigated. Findings: The FE results showed an improvement in the shear stress response of the sandwich panel with stair grooved foam core with stair keys compared to conventional model. Also the stair inserts between the GFRP skin and the foam core increases the initial shear stiffness and ultimate shear strength of the proposed model of the sandwich panel. Application/Improvements: The present methodology acts as a new model of peel stopper mechanism, where the shear failure due to debonding of face sheet and foam core is rerouted to foam core. Also it is free from initial damage as there is no loss of solidarity of the bulk material at the foam core, cost effective and easy to design and manufacture compared to other pinning and stitching process.