Experimental investigation on the behaviour of square FRP composite tubes under repeated axial impact

Series of impact tests were conducted to investigate the behaviour of fibre reinforced polymer (FRP) composite tubes under axial impact. The effects of damage parameters such as the mass of the impactor, incident energy and number of impacts on their behaviour were studied. The tests were performed by axially impacting 100 mm square FRP pultruded tubes to 130 repeated impacts or up to collapse using a drop-weight type impact apparatus. Impact masses and drop heights were varied to produce incident energies ranging from 158 to 635 J. The results showed that the peak load degradation of collapsed tubes is more rapid when it is impacted by higher incident energy. Heavier impactors caused more damage to the tubes at lower incident energies as reflected by their lower number of impacts to collapse, however, its effect gradually decreases at relatively higher energies. The incident energy is a major damage factor in the collapse of the tubes for lower number of impacts. However, the number of impacts becomes the key factor when the value of the incident energy decreases.