ABSTRACT
Composite materials sometimes suffer effects during the manufacturing process itself, called defects. These include voids being filled with volatile resin components, defects in fibre-to-resin bonding, delamination of plies, ply cracks, external impurities, and so on. Infrared (IR) thermography is an emerging convenient method for the nondestructive testing of composite materials. This technique is reliable, fast, and allows real-time measurement over a large surface area. Artificially produced subsurface defects in fibre-reinforced composite at different depths are detected and applied using an image reconstruction algorithm. The defects are captured as amplitude and phase images, with phase images being considered more reliable. The observation of defects at slower excitation frequency gives greater depth of results. It is an option for nondestructive testing of natural fibre–reinforced composites, offering reliable, safe, and cost-effective assessments.
Thermal diffusivity (α) measures the capacity of a composite to conduct thermal energy compared to its capacity to store thermal energy. Resistance across the surface of a composite material in contact with the electrodes is considered for surface resistivity. The length, width, and thickness of composites are considered for volume resistivity.
