Post-impact flexural collapse modes of composite sandwich structures in Arctic conditions: Analytical prediction and experimental validation

This study investigates the post-impact flexural collapse modes of Divinycell H-100 PVC foam core with woven carbon fiber reinforced polymer (CFRP) face sheet composite sandwich structure. Effects of low temperature and impact energy on flexural collapse modes are predicted analytically and validated experimentally. Low-velocity impact tests with 4 J and 8 J impact energy are performed at three different temperatures: 23 degrees C, 30 degrees C and 70 degrees C. Impacted specimens subsequently undergo three-point bending test to identify flexural collapse modes. Analytical models portray indentation, core shear and face wrinkling as the main competing failure modes, whereby the dominant mechanism is dependent on pre-existing impact damage, face sheet thickness, environmental temperature and bending configuration. Results reveal that thick face sheet specimens collapse mainly by indentation or core shear. However, thin face sheet specimens display different collapse mechanisms namely core tensile failure and debonding, which are attributed to degraded tensile strength of back face sheet and impactinduced interfacial debonding at extreme low temperature. This work aims to provide fundamental understanding on the relationship of low temperature and failure modes, so as to guide future design of composites for Arctic applications.