Mechanical responses of CFRP/PVC foam sandwich plate impacted by hailstone

Abstract

Mechanical responses of sandwich plate with carbon fiber reinforced polymer (CFRP) laminate as face-sheets and polyvinyl chloride (PVC) foam as core, which is promising in the lightweight design of high-speed maglev trains, was studied for the case of hailstone impact. Nine 500 × 500 mm sandwich plate specimens of three face-sheet thicknesses 1, 2 and 3 mm and a constant core thickness 30 mm were fabricated and tested under the impact of ice spheres of 50 mm in diameter propelled by the first-stage light gas gun. Three impact speeds, i.e. 30, 60 and 90 m/s, of the ice spheres and three incident angles, i.e. 0°, 30° and 45°, were investigated. For all cases, no macro failures were observed, but invisible damages, i.e. delamination in the upper face-sheets and indentation of the foam core, were found by high resolution ultrasonic testing. The experimental results were then used to calibrate the corresponding numerical model, based on which a thorough parametric analysis was performed to show the full dynamical responses of CFRP/PVC foam sandwich panels under hailstone impact. It is found that the foam cushion could effectively protect the rear face-sheet and increasing the ratio of span to thickness of the panel could reduce the damage degree due to the change of failure mode from local to global.