白桦材断裂韧度的各向异性性质

木材可视为正交各向异性材料，表征木材抵抗裂纹扩展能力的断裂韧度硒。是木材的基本力学性质之一，它具有明显的各向异性．对白桦材试样断裂韧度硒。测试结果表明，LT试样的断裂韧度明显高于TL，TR试样的断裂韧度，TL和TR试样的断裂韧度相接近．无论哪种试样类型，起裂均发生在裂纹尖端．TL，TR试样裂纹扩展方向与原裂纹初始方向一致，LT试样与前两不同，裂纹沿着几乎平行于纤维的方向扩展．并且含水率对各个方向木材断裂韧度的影响趋势是一致的．

ANISOTROPIC CHARACTERISTIC OF WOOD FRACTURE TOUGHNESS

With wood being considered as an orthogonal anisotropic material, its fracture toughness KIC, denoting wood resistance against crack extension is one of wood basic mechanical properties, with obvious anisotropy. The test results indicate that LT specimen fracture toughness is obviously higher than that of TL, TR specimen; those of TL and TR specimen are close. Regardless of specimen types, crack propagation all occurs at the crack tip. TL and TR specimen crack extension direction is consistent with the original crack direction, while LT specimen crack grows nearly parallel to the fiber direction, The influence tendency of moisture content on each wood direction fracture toughness is about the same.