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An experimental characterization of the opening-mode (Mode I) fracture toughness of bonded interfaces for hybrid laminates is presented. A bi-layer Contoured Double Cantilever Beam (CDCB) specimen, which is designed by the Rayleigh-Ritz method, is effectively used for the fracture toughness tests of the bonded interfaces. The bi-layer specimen consists of constant thickness adherends bonded to straight tapered sections of an easily machinable material, and it is contoured to achieve a constant rate of compliance change with respect to crack length. Using linear slope CDCB specimens, Mode I fracture tests for wood-wood and Fiber Reinforced Plastic (FRP)-wood bonded interfaces are performed to determine the critical loads for crack initiation and crack arrest, and from the critical loads measured, the critical strain energy release rates (GI,) are easily evaluated by making use of the experimentally verified constant compliance rate change over defined crack lengths. Based on finite element analyses, the predicted GI, values by the Jacobian Derivative Method correlate closely with experimental results. The FRP-wood bonded interface considered in this study exhibits a stable crack propagation behavior, and the Resorcinol Formaldehyde adhesive used offers a good potential for bonding FRP to wood sub-strates. The efficient CDCB specimen and experimental/analytical program presented in this paper can be used to evaluate the Mode I fracture toughness (Gkn) for hybrid material interface bonds, such as FRP-wood.

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Typically, wood-based composite materials have been developed through empirical studies. In these products, the constituent wood elements have broad spectrums regarding species, size, and anatomical orientation relative to their own dimensions. To define special strength and stiffness properties during a long-term study, two types of corrugated wood composite panels were developed for possible structural utilization. The constitutional elements of the newly developed products included Appalachian hardwood veneer residues (side clippings) and/or rejected low quality, sliced veneer sheets. The proposed primary usage of these veneer-based panels is in applications where the edgewise loading may cause buckling (e.g., web elements of I-joists, shear-wall and composite beam core materials). This paper describes the development of flat and corrugated panels, including furnish preparations and laboratory-scale manufacturing processes as well as the determination of key mechanical properties. According to the results in parallel to grain direction bending, tension and compression strengths exceeded other structural panels' similar characteristics, while the rigidities were comparable. Based on the research findings, sliced veneer clipping waste can be transformed into structural panels or used as reinforcement elements in beams and sandwich-type products.

The heat treatment of softwood (i.e. spruce, pine, fir, and larch) may result in significant colour changes. During this study Scots pine and spruce samples were steamed and analysed for their altered hue and lightness. Treatments included: 0 to 22 days of steaming time at a temperature range of 70 to 100°C. The outcome included a variety of colours between the initial hues and brownish tint. These new colours are similar to that of aged furniture and indoor wooden structures. Consequently, properly steamed softwood may be used to repair historical artefacts and relic furniture. Besides restoration, steamed stocks are excellent sources for manufacture of periodical furniture, where the aged appearance has aesthetical value. Results however, indicated that steaming at a temperature above 90 ˚C has a bleaching effect, i.e. the coloured chemical components formed by moderate steaming may be removed. Furthermore, we observed a linear correlation between lightness and colour hue at all steaming times and temperatures.