Shearography With Thermal Loading For Defect Detection Of Small Defects In Cfrp Composites

Abstract

Composite materials, e.g., carbon fibre-reinforced polymers (CFRPs), have been increasingly adopted in safety-critical structures across different industries. However, various defects including delaminations and fibre breakage can occur in the composite structures that may endanger the whole structure severely. Therefore non-destructive testing (NDT) of composites is critical to ensure structural integrity and safety. It is important to advance the capabilities of NDT of composite materials towards early-stage damage, e.g., small defects of millimetre scale, to avoid future failure. The objective of this work is to study the detection of small defects in CFRP laminates using shearography with thermal loading. In this paper, a thermal-mechanical FEM model was established in Abaqus to assist shearography inspection of the composite laminate. This FEM assistance is capable of evaluating different thermal loading schemes for defect detection. A rational selection of the reference and signal interferograms from the heating/cooling sequence is determined for reliable defect detection. We will present both experimental and numerical results on the detection of small defects in CFRP.