Crash Testing of Polymer Matrix Composites Using Flat Specimens

The industry's use of polymer composite materials is continuously increasing because of their excellent mechanical properties and light weight. However, among the multiple structural applications whose performance can be improved using composites, crashworthiness is one of the less common but with good perspectives for the future, thanks to the high level of energy absorption of these materials. In the present work, the crash behavior of three composite materials (a carbon/epoxy, a hybrid glass-carbon/vinyl ester and a carbon/vinyl ester laminate) was studied by performing in-plane compression tests of flat plates in impact conditions using a drop tower. The testing setup required a fixture to hold the specimen in vertical position and avoid buckling when loaded in in-plane direction. Two different versions of the testing fixture were compared. The first one requires a plate to transmit the load from the falling mass to the specimen, while in the second version the falling mass gets directly in contact with the specimen. The specimen crashed under the impact load, and the main failure mechanism was splaying with fronds. Both fixture versions worked effectively to crash the specimens and measure the Specific Energy Absorption (SEA) of the three materials. The carbon/epoxy and hybrid laminate showed a similar crash force, with the second having higher SEA because of the lower density. The carbon/vinyl ester material showed higher crash stress and SEA.