Review of Progress in Quantitative Nondestructive Evaluation
Due to the porous nature of wood and natural fiber based products, conventional fluid or gel coupled ultrasonic inspection is unsuitable. Air‐coupled ultrasonic transmission scanning, being non‐contact, is ideally suited for inspecting lumber, wood and natural fiber based products. We report here several successful applications of air‐coupled ultrasound for the inspection of wood. Air‐coupled ultrasonic scan at 120 kHz can easily detect “sinker‐stock” lumber in which bacterial damage of ray tissue cells had occurred during anaerobic pond storage. Channels in ash lumber board caused by insect bore were imaged in transmission scan. Delamination and material inhomogeneities were mapped out in manufactured wood and natural fiber products including medium density fiberboards, compression molded shredded waste wood with formaldehyde resin, and acoustic panels molded with kenaf fibers. The study has demonstrated some of the capabilities of air‐coupled ultrasound in the NDE of forest products.
American Institute of Physics
Hsu, David K.; Utrata, David; and Kuo, Monlin, "NDE of lumber and natural fiber based products with air coupled ultrasound" (2009). Center for Nondestructive Evaluation Conference Papers, Posters and Presentations. 73.