Speaker
Description
Active infrared thermography has emerged as a powerful, non-contact technique for the inspection of composite components, with Carbon Fiber Reinforced Polymers (CFRP) receiving particular attention due to their widespread use in the aerospace industry. In such critical applications, composite skins are frequently bonded to honeycomb core structures, which fulfill diverse roles ranging from geometric and structural support to acoustic attenuation. To meet these varied and demanding requirements, the design office must carefully select honeycomb core parameters—including material type (primarily aluminum or Nomex), as well as density, cell diameter, and height—in order to optimize the performance, durability, and functionality of the overall component.
This presentation investigates how the properties of honeycomb cores influence the effectiveness of active thermographic inspection, focusing specifically on the use of pulsed optical excitation for the detection of flaws located at the skin-to-core interface. A primary objective is to better understand the relationship between honeycomb architecture and the detectability of disbonds and other critical defects, which are particularly challenging to identify using conventional methods due to the complex structure and thermal behavior of these materials.
To thoroughly address these complexities, a comprehensive program of parametric and experimental studies has been conducted, targeting scenarios associated with increased detection difficulty. Experimental results highlight that thermal responses vary significantly between monolithic CFRP regions and those incorporating honeycomb cores. In particular, aluminum honeycomb structures are found to facilitate higher rates of thermal diffusion, which in turn enhance the thermal contrast and overall visibility of skin-to-core disbonds during infrared inspection. This effect becomes more pronounced as honeycomb density increases, confirming the critical role that core architecture plays in heat propagation and defect detectability. Conversely, Nomex honeycomb, characterized by low thermal diffusivity, presents substantial challenges for disbond detection, especially when thick monolithic layers—typically exceeding 3 mm—are present above the core. Detecting disbonds in such configurations often requires not only more sensitive inspection methodologies, but also a sophisticated understanding of thermal behavior, aided by advanced analytical and simulation tools.
Based on experimental findings, the authors will also propose simulation-based opportunities for a more comprehensive understanding of honeycomb effects aiming to reduce the fabrication of dedicated defective samples.
