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One Gifford Pinchot Drive
Madison, WI 53726-2398
Phone: (608) 231-9200
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Title: Linking Log Quality With Product Performance

Source: In: United States Forest Service, Forest Products Laboratory General Technical Report, FPL-GTR-100; July 1997

Author(s)Green, David W.; Ross, Robert J.

Publication Year: 1997  View PDF »

Category: Journal Articles

Abstract: In the United States, log grading procedures use visual assessment of defects, in relation to the log scaling diameter, to estimate the yield of lumber that may be expected from the log. This procedure was satisfactory when structural grades were based only on defect size and location. In recent years, however, structural products have increasingly been graded using a combination of visual estimation of defects, coupled with nondestructive evaluation of other parameters, to obtain a more precise estimate of product properties. Today, the most commonly used nondestructive evaluation parameter is modulus of elasticity (MOE). This paper summarizes the results of three studies that used longitudinal stress wave techniques to determine the MOE of logs prior to processing into lumber. The MOE of lumber was then determined by transverse vibration. A good relationship was generally observed between the MOE of logs and the average MOE of the lumber cut from an individual log. These results indicate that improved sorting of logs for structural products might be achieved using a combination of visual assessment and determination of the MOE of the logs using longitudinal stress wave techniques. Future research will quantify the improvement in log sorting efficiency relative to other nondestructive testing options.

Keywords: Log grade, longitudinal stress wave, modulus of elasticity, lumber, spruce, balsam fir, Douglas-fir, western hemlock, Southern Pine.

File size: 331 kb(s)

Date posted: 04/13/2011
Current FPL Scientist associated with this product
Ross, Robert J.
Supervisory Research Gen. Engineer

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