Effect of annual ring angles on static bending strength performances of cross-laminated woods made with spruce

Abstract

In this study, cross-laminated woods were made with spruce wood and the effects of annual ring angles of perpendicular direction laminae on static bending strength performance were investigated. Static bending strength performances of parallel laminated woods with all layers composed of laminae perpendicular to the grain (P ⊥ type) were in the order of 90° > 0° >45°. The MOE and MOR for the 45° annual ring angle were 0.0989 GPa and 3.25 MPa, and it showed the lowest values. By placing longitudinal-direction laminae in the core of P ⊥ type, the strength performances were markedly improved. In the case of cross-laminated woods with perpendicular-direction laminae in the faces (C ⊥ type), the bending strength performances were in the order of 90° > 0° > 45°, but the differences among annual ring angles were less than those of the parallel-laminated woods. In the case of cross-laminated woods with perpendicular-direction laminae in the core (C ⊥ type), the bending strength performances were in the order of 45° > 90° > 0° unlike P ⊥ type and C ⊥ type. The MOE and MOR for the 45° annual ring angle were 12.0 GPa and 55.8 MPa, and it showed the highest values.