Blast & Impact Loading & Response of Structures
To accommodate the growing interest in sustainability, it is important to reduce the environmental impact from new infrastructure. One way to improve the sustainability of structures is to incorporate natural and bio-based materials. As the weak core material often governs failure in structural sandwich panels, there is an opportunity to replace the traditional synthetic face materials with bio-based materials for some applications, such as cladding systems. In this paper, the residual properties of sandwich panels with flax fibre-reinforced polymer (FFRP) faces which have been subjected to impact loading will be investigated. The sandwich panels tested in this study were fabricated using a closed cell polyisocyanurate foam with a density of 64 kg/m3 and faces made of a balanced bidirectional flax fabric (nominal areal mass of 400 g/m2) and an epoxy resin with an approximate bio-content of 30% after mixing. Each specimen is 1220 mm long, 150 mm wide and approximately 80 mm thick. The sandwich panels will first be subjected to an impact of 90% of their ultimate capacity using a drop weight impact test. The span length of the tests will be 1117 mm and a drop weight with an impact surface width of 150 mm will impact each specimen at midspan. For these tests, the top face strain, bottom face strain and deflection at midspan will be sampled at a rate of 25 kHz. After the impact, the panels will be tested under quasi-static three-point bending to failure. During this test the load, midspan deflection, and top and bottom face strains at midspan will be sampled at a rate of 10 Hz. The results of the post-impact quasi-static flexural test will be compared with similar flexural tests performed on intact specimens to determine the effect of the impact on the flexural behavior of the sandwich panels. From previous impact tests, it was observed that the stiffness of the specimens was not significantly changed after multiple impacts and therefore it is hypothesized that the flexural properties of these specimens will not be significantly affected by an impact event. However, this study is a work in progress and results will be available upon submission of the full paper.