Characterization of Fabrication Induced Defects and Assessment of Their Effects on Integrity of Composite Structures

Voids and ply waviness are the most common types of fabrication process induced defects in composite structures that can have detrimental effects on their load bearing capacity. To date, extensive works have been done on the characterization of fabrication induced defects on the mechanical properties of composites but less study has been performed to determine the effects of defects on the failure progression. Given the durability and damage tolerance requirements for certification and design of composite structures, it is important to evaluate the effects of these defects on the damage initiation and failure progression of a loaded composite structure. In this study, void and ply waviness information are extracted from X-ray computed tomography (CT) and optical microscopy and an efficient image-to-numerical solution is developed to map the detected voids and ply waviness into a finite element based progressive failure analysis model. An interlaminar tensile (ILT) test specimen under four point bending is used to demonstrate the capability of our response and progressive damage prediction.