Two-Way Flexural Behavior of Sandwich Panels with Flax FRP Faces and Foam Cores Under Monotonic Loads

Abstract

In this study, the flexural properties of sandwich panels with flax fiber-reinforced polymer (FFRP) faces and polyisocyanurate foam cores are examined. Three large-scale 1220 mm by 1220 mm sandwich panels with thicknesses of approximately 80 mm were fabricated and two have been tested. A balanced bidirectional flax fabric with a nominal areal mass of 400 g/m² and an epoxy resin with a bio-content of approximately 30% were used to make the faces and a 76 mm thick polyisocyanurate foam with a nominal density of 96 kg/m³ was used as the core material. Each panel was tested under a concentrated load at the center and the test span in each direction was 1120 mm. During the tests, the load, center deflection, and face strains in the fiber directions were measured at a sampling rate of 10 Hz. The main parameter of the tests was the effect of facing thickness: one (approximately 1.5 mm thick), two (approximately 2.5 mm thick) or three (approximately 3.5 mm thick) layers of FFRP on the structural behavior of the panels. It was shown that doubling the number of face layers increased the strength by 68% and the stiffness by 48%. This is an on-going study and more results will be available at the time of the conference.