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dc.contributor.authorLlana, Daniel F.
dc.contributor.authorShort, Ian
dc.contributor.authorHarte, A. M.
dc.identifier.citationLlana, D.F., Short, I. and Harte, A.M. 2019. Acoustic measurement differences on trees and logs from hardwoods in wet and dry condition. In: Wang, X., Sauter, U.H. and Ross, R.J. (eds). Proceedings: 21st International Nondestructive Testing and Evaluation of Wood Symposium. General Technical Report FPL-GTR-272. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. pp. 561-568.en_US
dc.description.abstractAcoustic velocities measured on standing trees using time-of-flight (TOF) devices have been found to be between 7% and 36% higher for softwoods than those in logs using resonance techniques based on longitudinal frequencies. This effect was explained in three different ways: (1) TOF devices on standing trees measure outerwood containing more mature wood while resonance methods assess the whole crosssection, (2) the variation in the velocity is due to loading conditions in standing trees, while logs are free of loads and (3) the acoustic waves are dilatational waves in the case of TOF measurements on standing trees and one-dimensional longitudinal waves in the case of resonance on logs. This is an important topic considering the fact that resonance methods are considered more accurate for predicting mechanical properties and it has been proposed that correction factors should be applied on TOF measurements. In the present work, four hardwoods from Irish forests were studied and, on average, TOF velocities measured in the forest above fibre saturation point (FSP) were 19.8% higher than those from resonance measurements taken on logs immediately after felling. However, this difference reduced to 5.4% when the measurements were repeated at a moisture content (MC) of about 18% in the laboratory. Therefore, there is a MC effect on the velocity differences. Furthermore, higher differences were systematically found in older specimens in wet condition. However, this age effect was small in most cases.en_US
dc.publisherU. S. Department of Agricultureen_US
dc.rightsAttribution-NonCommercial-ShareAlike 3.0 United States*
dc.subjectAcoustic velocitiyen_US
dc.subjectmoisture content influenceen_US
dc.subjectstanding treesen_US
dc.titleAcoustic measurement differences on trees and logs from hardwoods in wet and dry conditionen_US
dc.contributor.sponsorDepartment of Agriculture, Food and Marineen_US

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