Low Velocity Impact Behaviour of Asymmetric Three-layer Sandwich Composite Structures with and without Foam Core

This paper presents an experimental investigation of the impact behaviour of three layer sandwich structures made of high density polyethylene (HDPE) and hemp, with and without a foam core. Low-velocity falling weight and Charpy impact tests were performed to investigate the influence of hemp content, skin thickness and core density. The strength, load, absorbed energy, and deflection histories were recorded and analysed and the damaged specimens were inspected to determine the failure patterns. Based on the Charpy impact results, the structures with foam core had higher energy absorption capabilities compared to their counterparts without foam core. In addition, based on the falling weight impact results the energy dissipation properties of sandwich structures without foam core were superior to the structures with foam core. This property was also greatly influenced by skin fibre content, skin thickness and structure configuration.