Evaluation of temperature effects on low velocity impact damage in composite sandwich panels with polymeric foam cores

Abstract

In this study we investigate the response of closed cell polymeric foam core sandwich panels with woven carbon/epoxy laminate facesheets under low velocity impacts. Two levels of energy, 10J and 50J simulating barely visible and visible impact damage categories are examined under cold, room and high temperature conditions. A finite element modeling framework is proposed for the sandwich composite comprising continuum damage, cohesive layers and crushable foam model with isotropic hardening for the core. The model shows how progressive damage in the facesheets, interlaminar damage between the layers and the crushable foam can be used to model low velocity impact and temperature effects. Ultrasonic testing and high speed cameras are used to determine the damage and delamination characteristics. The higher exposure temperatures result in larger damage zones for both the low and high impact energies. The elevated temperature enhanced the penetration rate and indentation depth showing degradations in the out of plane properties. The visible damage test results in significant damage in the core and facesheets dependent on the temperature ranges tested. In the barely visible damage category, the composite facesheet layers attached to the foam experience a tension failure under low energy impact despite surface indications showing no fiber fracture.