In-situ Observation of Dynamic Damage Evolution Inside GFRCs Through High-Speed X-ray PCI

Abstract

We visualized, in real time, the dynamic damage evolution inside glass fiber reinforced composites (GFRCs) subjected to low-velocity impact by high-speed X-ray phase contrast imaging (PCI) technique. Dynamic single-edge notched bending (SDENB) experiments were performed on a modified Kolsky compression bar. The specimen was mounted on a fixture at the end of the incident bar, impacted onto an indenter pin on a fixture installed ahead of a load cell which was used to replace the transmission bar. During the dynamic loading, synchrotron X-ray penetrated the specimen, detecting the internal damage of the composite material. The X-ray signal was then transferred to visible light through a scintillator and finally recorded by a high-speed camera. Different failure behaviors of unidirectional and cross-ply composites with varied ply thickness were studied. It is revealed that high-speed X-ray PCI technique can visually identify the crack initiation, crack propagation within and among multiple plies and various micro-scale damage mechanisms in high-resolution of 10-micron-meter scale.