The load carrying capacity, stiffness, and strain fields of 18 mm thick and half lap 30 mm thick L-shaped furniture self-locking frame joints made of a Finnish birch plywood and a birch battenboard were determined. The joints were tested under tensile and compression bending. On the basis of the experimental information, finite element analysis models were verified. The data showed that the joints made of birch plywood reached a higher load carrying capacity and stiffness than the joints made of the birch battenboard with the same thickness. The Half lap joint (H L J) made of the Finnish plywood reached the ultimate load carrying capacity and the ultimate stiffness under both the compression bending and the tensile bending. The finite element analysis models of the joints can be used for estimating the mechanical properties of the self-locking joints with different tenon shapes made of the materials used in this paper.
AbstractNatural constituents of wood cell-wall layers are affected in various ways by thermal treatment. This study investigated the effect of high-temperature treatment on the properties of cell-wall layers. The properties were studied using PeakForce quantitative nanomechanical mapping and Fourier-transform infrared spectroscopy (FTIR). European beech wood was thermally treated at 200 °C for 1, 3, and 5 h in an oxidizing atmosphere. Modulus of elasticity, adhesion force, and roughness of the secondary S2 layer and the compound middle lamella (CML) were determined using atomic force microscopy (AFM). Results showed that both the S2 layer and CML were affected by thermal treatment. Stiffening of the S2 layer was caused by increased crystallinity of the cellulose-dominated component, having peaked after 1 h of treatment. The degradation thereafter resulted in a decrease of the S2 as well as the CML stiffness. An increase of CML roughness after 3 h of treatment was associated with the effect of thermal degradation on CML integrity. The analysis suggested that the reduction in syringyl lignin is potentially associated with an increase in adhesion of cell-wall layers.
The article presents the main results of experimental studies on the identification of the main grade defects of oak lumber by the thermal non-destructive testing method. Regressional dependences of wood defects temperature display from the main factors for the studied grade defects are proposed. Indicators of infrared radiation (temperature range) of the main visible oak grade defects obtained as a result of experimental studies are presented. A conceptual scheme for the line control methods of identification of the main grade defects in lumber are proposed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.