Impact Performance and Damage Behavior of Composite Sandwich Structures in Arctic Condition

Abstract

In this work, the impact behavior of composite sandwich structures at low temperature condition is investigated and explored. Composite sandwich structures are commonly used in naval vessel constructions, due to their light-weight and high bending stiffness. The state-of-the-art Instron CEAST impact machine, equipped with an environmental chamber, is employed to perform impact testing on composite sandwich panels at low temperature range. The objective of this work is to study how low temperature affects the impact behavior and damage response of composite sandwich structures, with a longer overarching aim to develop new sandwich construction with enhanced impact damage tolerance for future naval applications in arctic environment. Results from this study reveal that composite sandwich structures experienced greater damage when impacted at low temperature (-70°C) compared to the same specimens impacted under same test condition at normal room temperature (23°C). The extent of damage is clearly evident by post-mortem observation. Impact history curves are also analyzed to understand the dynamic behavior of composite sandwich structures during the impact event. Force-time graphs indicate a lower peak force for low temperature specimens. This implies that the maximum strength of the composite sandwich structure is significantly reduced and it is easier to cause damage at low temperature condition. Force-time and energy-time data also delineate the roles played by energy absorption of the carbon/fiber epoxy face sheet and the PVC foam core during the impact event. At low temperature, the face sheet absorbs less energy, due to reduced material strength; while the foam core absorbs most of the energy by foam crushing mechanism. At normal room temperature, the face sheet absorbs considerable amount of energy before failure and the foam core absorbs the remaining energy with lesser extent of damage.