Characterizing Fiber Orientations and Layer Stacking Sequences in CFRP Laminates through Induction Heating Patterns: A Nondestructive Approach

Abstract

The induction heating using a circular coil in Carbon Fiber Reinforced Polymer (CFRP) laminates produces unique heating patterns, significantly influenced by the fiber orientations in each layer and electrical contacts between layers. This study investigates these patterns using thermography and reveals a transition from circular to rectangular heating patterns under the influence of a circular induction coil. This shift is driven by changes in interlaminar microstructure, particularly increasing fiber separation at interfaces, interpreted as fewer electrical contacts. The research also presents a novel nondestructive, noncontact method for identifying fiber orientations within CFRP laminates. The method employs a 2D Fast Fourier Transform (2D-FFT) to extract fiber orientations from the spatial characteristics of the heating patterns. The study demonstrates the effectiveness of this method for accurately determining fiber orientations in quasi-isotropic CFRP laminates. This methodology opens potential applications for large-area inspection and quality control in fiber-reinforced composite manufacturing.