Low velocity impact induced damage evaluation and its effect on the residual flexural properties of pultruded GRP composites

Low velocity impact induced non-penetration damage in pultruded glass fibre reinforced polyester (GRP) composite materials was investigated using an instrumented falling weight impact test machine with a chisel shaped impactor. The characteristics of the impact event, force/time and force/deflection traces were determined. The internal damage was visualised and quantified by Electronic Speckle Pattern Interferometry (ESPI) in terms of the thickness, density and uniformity degradations of fringe patterns. There is a linear relationship between the impact energy and the identified damage areas. The post impact structural integrity of impacted specimens was evaluated by three point bending tests. It reveals that there is a significant reduction in flexural properties due to the impact-induced damage and that the residual flexural strength is more susceptible to damage than residual modulus.