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Non-destructive glue line assessment in timber laminates with an air-coupled ultrasonic technique

S. J. Sanabria and C. Mueller and J. Neuenschwander and P. Niemz and U. Sennhauser
Delamination in wood, wood products and wood-based materials
V. Bucur, Ed.
Springer, Berlin, Germany, 2010


Wood is a sustainable construction material. Glued timber products make efficient use of the strength properties of solid wood; moreover, structural members of expanded dimensional and geometrical properties can be produced. The integrity of the glue lines of timber laminates needs to be assessed during the full life cycle of the product; therefore, a non-destructive reproducible inspection method is required. As part of an ongoing project, we performed air-coupled ultrasound (ACU) measurements in glued timber laminates. A normal transmission setup with 120 kHz commercial transducers was used to analyze samples consisting of two spruce solid wood lamellas glued together with polyurethane adhesive introducing defined delaminated areas. Ultrasonic scanning with high resolution was performed to successfully image the presence or absence of glue. The geometry of the delaminated regions and features of the wood structure could also be visualized.We have demonstrated that ACU is a sensitive, accurate, reproducible and non-invasive inspection alternative with respect to conventional contact techniques; therefore, it is wellsuited for glued timber inspection. Future work is planned for the inspection of more complex glued timber structures.

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  title = {Non-destructive glue line assessment in timber laminates with an air-coupled ultrasonic technique},
  booktitle = {Delamination in wood, wood products and wood-based materials},
  pages = {},
  year = {2010},
  publisher = {Springer, Berlin, Germany},
  keywords = {379-387}