The static and dynamic response of CFRP tube reinforced polyurethane

This paper presents an investigation on the mechanical properties of thermosetting polyurethane (TSPU) and thermoplastic polyurethane (TPU) under quasi-static and low velocity impact (LVI) loading. Hollow glass microspheres were added at different volume percentages to the TSPU to decrease the density and to investigate the effect on the mechanical properties. Incorporating the fillers leads to the development of a stepwise graded foam, which has been shown to yield more constant plateau stress levels under dynamic loading. The work was extended to investigate reinforcing the TSPU and the TPU matrix with carbon fibre reinforced plastic (CFRP) tubes, providing a higher load-bearing capacity under static loading. Reinforcing the syntactic TSPU resulted in a 47.7% increase in specific energy absorption (SEA), with the average value reaching 56.28 kJ/kg. The specific compressive strength for the reinforced TSPU was also improved under quasi-static loading, where a 65% increase was observed, relative to the unreinforced TSPU. For the reinforced TPU significant improvements were seen under dynamic loading conditions, relative to the unreinforced TPU, with increases in plateau stress levels of 629% and 452% at strain levels of 25% and 50%, respectively.