Health monitoring of the composite honeycomb insulation panels using thermographic image processing

Honeycomb-structured materials are extensively utilised in both commercial and military aircraft. The occurrence of manufacturing defects and operational damage has emerged as a significant safety concern, consequently elevating the necessity for non-destructive testing (NDT) to identify flaws and damage during aircraft operation and maintenance. In addition to merely detecting defects, it is crucial to accurately characterise or classify them. In this paper, the honeycomb sandwich samples were designed and manufactured from two CFRP face-sheets and Nomex core with thick resin containing nano clay 30B mixed with ultrasonic coverage. Defects were placed into carbon sheets, resin, and core materials. An NDT technique based on infrared thermography was applied, along with PCA image processing, which automatically categorises prevalent defects found in honeycomb materials. These defects encompass debonding, adhesive issues, and fractures within the honeycomb core. Thermography results showed that defects such as delamination, core fracture, lack of adhesion, and resin inhomogeneity can be identified, especially with high accuracy using PCA image processing.