Strain-rate sensitivity of electrically modified carbon/epoxy composites under dynamic compressive loading

This experimental work focuses on the strain-rate effect of unidirectional carbon/epoxy composite with enhanced electrical conductivity. With respect to the reference composite material, the modification on the electrical properties was realized through interleaving a sliver-loaded conductive veil into the composite laminate, which was developed and supplied by AVIC Composite Center (ACC). Benchmarking was also carried out against the non-modified unidirectional (UD) carbon/epoxy composite, labelled as “reference material”, to study the influence of this modification on the compressive stress-strain behavior of the material. Dynamic compression tests were carried out using a split Hopkinson pressure bar (SHPB) system along with a high-speed camera to monitor the progressive failure of the test samples under impact loading. Quasi-static experiments were also performed using a servo-hydraulic loading frame in accordance with ISO 14126. The findings show a decline on the elastic modulus of the electrically modified composite material when compared with that of reference material, regardless of the exposed loading rates. As for the strain-rate effect, both material configurations were found to be rate dependent. At high loading rates, the longitudinal compressive strength increased by around 60% and 91% for modified and reference UD carbon/epoxy composites, respectively. Despite that, the loading rate appears to have an insignificant effect on the elastic modulus of both material configurations.