Impact behaviour of high performance glass fibre reinforced cement composite laminates

Instrumented drop weight impact tests were performed on 15 identical phosphate cement composite laminates, reinforced with glass fibre chopped strand mats (fibre volume 24%), clamped along their four edges. The level of the impact energy was varied between 3.7 J and 69.5 J by changing the drop height of the impactor. Contact force-deflection curves were obtained for each impact test, and assembled to a master curve for all tests. The obtained shape of this master curve is very similar to that for polymer matrix composites, indicating that after a quasi-elastic energy absorption phase, local damage is occurring after reaching the peak force, followed by elastic rebound of the impactor. A difference exists however in the absence of closed curves, due to matrix cracking.
The interpretation of the data is performed following the energy profiling method proposed by Liu [1]. The values obtained for the damage initiation threshold (23 J), the penetration threshold (44 J), the perforation threshold ( 69 J), as well as the energy absorption efficiency of 75% (the percentage of absorbed energy up to the perforation) are comparable with polymer matrix composites of similar dimensions.