A comparative study of the impact properties of sandwich materials with different cores

K.R Ramakrishnan,S Guerard,P Viot,K Shankar

doi:10.1051/epjconf/20122601031

Abstract

Sandwich panels are made of two high strength skins bonded to either side of a light weight core and are used in applications where high stiffness combined with low structural weight is required. The purpose of this paper is to compare the mechanical response of several sandwich panels whose core materials are different. Sandwich panels with glass fibre-reinforced polymer face sheets were used, combined with five different cores; polystyrene foam, polypropylene honeycomb, two different density Balsa wood and Cork. All specimens were subjected to low velocity impact and their structural response (Force-displacement curves) were compared to quasistatic response of the panel tested using an hemispherical indenter.

Highlights

Sandwich panels are based on a simple structure of two thin high strength facesheets bonded to either side of a thick low density core such as foams and honeycombs
Sandwich panels are made of two high strength skins bonded to either side of a light weight core and are used in applications where high stiffness combined with low structural weight is required
Sandwich panels with glass fibre-reinforced polymer (GFRP) face sheets and the five different cores were quasistatically loaded at a constant displacement rate of 5 mm/min in a electro-mechanical machine (Zwick Roell, Germany)

Summary

Introduction

Sandwich panels are based on a simple structure of two thin high strength facesheets bonded to either side of a thick low density core such as foams and honeycombs. Bernard and Lagace used Xray photos to determine the extent of delamination damage and noted that extensive delamination and core damage were found in specimens with no visible surface damage [2] It was recommended by Park et al [3] that since the damage behaviour of sandwich structures are affected by the mechanical properties of both core and laminated facesheets, the damage behaviour under impact loading deserve careful investigation to ensure the reliability and safety of sandwich structures. Bernard and Lagace studied the impact resistance of composite sandwich plates with graphite/epoxy facesheets and three different cores; aluminum honeycomb, Nomex R honeycomb and Rohacell R foam core using low energy impact tests [2]. Atas and Sewin [8] compared the low velocity impact response of PVC foam, balsa core sandwich structures with glass fibre reinforced epoxy facesheets. Castro et al [9] compared the flexural and impact properties of cork core sandwich composites with Nomex R honeycomb and Rohacell R foam and observed that cork-epoxy agglomerates present a significantly better core shear stress limit, which reduces the crack propagation region

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