Comparison of local variation of modulus of elasticity determined on basis of scanned fiber angles and full strain field measurements
2013 (English)In: The 18th International Nondestructive Testing and Evaluation of Wood Symposium, Madison, WI, USA, 2013Conference paper (Refereed)
Strength grading methods are normally based on relationships between one measured value of modulus of elasticity (MOE), regarded as being valid for the whole board, and bending strength. Studies have shown, however, that with a detailed knowledge of local variation of MOE within boards, a highter coefficient of determination (R2) with respect to bending strength can be obtained. Measurements of fiber angles from laser scanning has shown to be a powerful tool to establish MOE profile along boards in a speed that cooresponds to the production speed at a sawmill. The present study aims at investigating the accuracy of the local MOE profile determined on basis of fiber angles from laser scanning. The study was carried out on a board of Norway spruce of dimension 50 by 150 by 3,900 mm. First the fiber angles on all four surfaces were identified using a WoodEye scanner and on the basis of these measurements, a MOE profile was calculated. Thereafter, the board was subjected to a constant bending moment and suring loading an image correlation system, Aramis, was employed for detection of the strain field with high resolution along the whole board. This strain field was then used to estanlish a 'true' MOE profile along the board. The MOE profiles determined in two different ways were compared and they show a close compliance. However, some difference were found and these were used for calibration of the method for MOE determination on the basis of scanning results. The present research thus contributes further improvement of a newly suggested grading method.
Place, publisher, year, edition, pages
Madison, WI, USA, 2013.
Finite element analysis, strength grading, fiber angle scanning, strain field, image correlation
Building Technologies Wood Science
Research subject Technology (byts ev till Engineering), Forestry and Wood Technology; Technology (byts ev till Engineering), Civil engineering
IdentifiersURN: urn:nbn:se:lnu:diva-30468OAI: oai:DiVA.org:lnu-30468DiVA: diva2:664872
The 18th International Nondestructive Testing and Evaluation of Wood Symposium, September 24-27, 2013, Madison