Mechanical Properties of Small Laminated Beams Utilizing Slicewood

The mechanical properties of small laminated beams made from slicewood were compared with sawed controls. Six plain-sawn, green yellow-poplar boards 48 inches by 1-3/4 inches thick by 9 inches wide were used. These were each crosscut into three flitches 15 inches long and were heated in water to 40?C. Four treatments were used: 1) sawn uncompressed, 2) sliced uncompressed, 3) sliced precompressed perpendicular to grain, and 4) sliced precompressed parallel to grain. Slicing was done both with the knife perpendicular to the grain (longitudinal slicing) and with the knife parallel to the grain. Slices were 0.2 inch thick. All sliced and sawn controls were kiln-dried, seasoned to 8 percent moisture content, and beams were glued using phenol resorcinol adhesive. An examination of knife checks resulting from perpendicular slicing revealed more checks and shallower depth from flitches precompressed perpendicular to the grain than from those which were not precompressed. However no detrimental effect of the knife check was evident in the static bending data since the specimens were tested with the glue line normal to the supports and loading head. The beams produced from slicewood were more flexible and had a higher elastic resilience than the sawed controls. In parallel slicing the knife checks were perpendicular to the span and resulted in a significant reduction in mechanical strength when compared with sawed controls, particularly when tested with the glue line parallel with the supports. The results indicate the need for further research particularly in the control of knife check.

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