Stress distributions and failure types of curved laminated veneer lumber for use in furniture under loading

Abstract

To control reliably the suitable use of curved laminated veneer lumber (LVL) as a structural member of furniture, stress distributions and failure types of curved LVL made from massion pine (Pinus massoniana Lamb.) and fast-growing poplar (Populus euramericana CV. I.) were investigated under end-pull, end-thrust, and transverse loading. The results are summarized as follows: In curved LVL of two wood species, absolute values of the maximum axial stress (σA) occurring at the convex surface are smaller than those (σB) that occurred at the concave surface. The differences between these values decrease with an increase in the radius of curvature. With end-pull loading, there were mainly splitting failures at glue lines near the centroidal axis. With end-thrust loading, there were more fibrous fractures on the tensile side and crushing failures on the compression side. With transverse loading, curved specimens of massion pine exhibited mainly splitting failures. In contrast, for curved LVL of fast-growing poplar, fibrous fractures occurred mainly on the tensile side. Absolute values of σA and σB significantly increased with an increase in the radius of curvature. In contrast, absolute values of the maximum radial stress (σR) decreased with an increase in the radius of curvature. Absolute values of σA, σB, and σR of curved LVL of massion pine were larger under end-thrust loading than under end-pull and transverse load-ing. Conversely, absolute values of σA and σB of curved LVL of fast-growing poplar were small under end-thrust loading. However, absolute values of σA and σB of curved LVL of two wood species under end-pull loading were almost similar to those under transverse loading. © The Japan Wood Research Society 1999.