Assessment of fiber orientation and order in carbon fiber reinforced polymer composites using induction thermography and Radon transform analysis

Abstract

The mechanical properties of carbon fiber reinforced polymer (CFRP) composites are critically influenced by th e fiber orientation and stacking sequence of individual layers. Any misalignment in the global ply orientation can lead to significant performance degradation and potential operational failure. This paper introduces an advanced method for identifying fiber orientation and its order in CFRP structures using Radon transform analysis of infrared thermal patterns generated through induction heating with a circular coil in transmission mode. The fiber orientation within the composite layers directs the flow of induced current, thereby affecting the resulting heating patterns. Radon transform allows to extract the hidden spatial characteristics of the heating patterns and thus the fiber orientations. The proposed method has been demonstrated on CFRP samples up to six layers. The results indicate a precision of the order of $7^o$, indicating the Radon transform method’s high accuracy in estimating fiber orientation in CFRP composite structures. This approach not only provides a reliable means to assess the internal fiber orientation, but also effectively identifies the sequence in which the orientation appear, contributing to a comprehensive understanding of the laminate structure. The ability to detect fabrication inconsistencies, such as fiber waviness, further highlights the robustness of this technique.