Mechanical Characterization of Natural and Synthetic Fibres using Sandwich Structures Under Bending

Fibre-reinforced sandwich panels are a well stablished design solution for applications that require high stiffness and low weight, but the high cost and enviromental impact of synthetic fibres have prompted the research for sustainable alternatives, such as natural fibres. While they offer potential for cost reduction and environmental sustaintalibity, their mechanical properties may compromise structural reliability. In this context, this work compares the equivalent stiffness of different composite sandwich panels under bending, using carbon, glass, linen, jute and cotton fibres as reinforcement. The specimens were produced using the Vacuum Assisted Resin Transfer Moulding (VARTM) and tested under four point bending conditions. Analytical methods were used for mechanical characterization, followed by Finite Element Method (FEM) validation. The results show that carbon fibre yields a greater stiffness-to-weight ratios followed by glass, jute, linen and cotton fibres. Sandwich panels with natural fibres reinforcement showed relative bending performances ranging from 19% to 35% of the carbon fibre ones.