THE ENERGY-ABSORBING CHARACTERISTICS OF HONEYCOMB CORES BASED ON CARBON FIBRE COMPOSITES

This paper investigates the energy-absorbing behavior of two types of carbon fiber reinforced honeycomb core manufactured using the VARTM method. One type of honeycomb was based on an epoxy resin and the other on an infusible thermoplastic, ELIUM^®. The honeycomb cores were produced using a steel onto which solid hexagonal blocks were secured. Carbon fiber fabrics were placed into the gaps between the blocks and the mold was subsequently vacuum-bagged and infused with either the thermoplastic or thermosetting resin. After manufacture, the steel blocks were removed from the samples giving a well-defined honeycomb structure. Test specimens were then removed from these honeycomb structures and inspected non-destructively using an X-ray computed tomography machine before testing at quasi-static rates of loading. Compression tests on the two types of honeycomb structure resulted in a stable mode of crushing failure, with energy being absorbed in fiber fracture and splitting. Both the thermosetting and thermoplastic-matrix cores exhibited similar values of specific energy absorption (SEA) with this value exceeding 50 kJ/kg for a thermoplastic-matrix core based on a fiber weight fraction of approximately 57%. This evidence suggests that fiber-reinforced honeycomb cores offer significant potential for use in energy-absorbing applications.