Behaviour of fibre-reinforced honeycomb core under low velocity impact loading

In this study, the behavior of two different types of cores, short flax fiber reinforced and continuous flax fiber reinforced polymeric cores, has been investigated under low velocity out-of-plane impact loading. The fiber-reinforced corrugations were manufactured by using matched-die compression molding and the resulting cells were bonded using ultrasonic methods to form recyclable honeycomb cores. A drop weight impact tester, Imatek IM10T-20 ITS, capable of producing velocities of up to 20m/s coupled with a high-speed camera (Phantom), was used to capture video images of the impact. The displacement of the impactor was recorded with a digital displacement transducer and the force was recorded with a digital force transducer. The effects of reinforced material type, the core height and the presence of facings including all their interactions on the energy absorption were determined by using statistical analysis based on the Taguchi method. The impact results revealed a better energy absorption when honeycombs with cell walls reinforced with continuous fibers were used; the presence of face-sheets played an important role in energy absorption only at lower core height. This was confirmed by the results of the statistical analysis revealing antagonistic interaction between the core height and facings.