Eddy current non-destructive evaluation of manufacturing flaws and operational damage in CFRP composites

Abstract

The manufacturing process of carbon fiber reinforced polymer (CFRP) composite structures can introduce many characteristic defects and flaws such as fiber misorientation, fiber waviness and wrinkling. Therefore, it becomes increasingly important to detect the presence of these defects at the earliest stages of development. Eddy current testing (ECT) is a nondestructive inspection (NDI) technique which has been proven quite effective in metallic structures. However, NDI of composite structures has mainly relied on other methods such as ultrasonics and X-ray to name a few, and not much on ECT. In this paper, we explore the possibility of using ECT in NDI of CFRP composites. We base our research on the fact that the CFRP displays some low-level electric conductivity due to the inherent conductivity of the carbon fibers. This low-level conductivity may permit eddy-current pathways that can be exploited for NDI detection. An invention disclosure describing our high-frequency ECT method is being progressed. We use multiphysics FEM simulation to simulate the detection of various types of manufacturing flaws and operational damage in CFRP composites such as fiber misorientation; waviness; wrinkling, etc. ECT experiments were conducted on CFRP specimens with manufacturing flaws using the Eddyfi Reddy eddy current array (ECA) system.