Studies on Development of Wood Joint of High Performance

1.为了开发高性能的木质接头，研究了坡度比和胶粘剂对指底倾斜的指尖接头性能的影响。使用的胶粘剂是间苯二酚酚醛树脂、环氧树脂和聚氨酯树脂。斜率比分别为0、0.5、1.0、1.5和2.0。通过静态弯曲、冲击弯曲和拉伸试验对斜指关节的性能进行了检测。1)当斜率比为1.0时，接头的抗拉强度和抗弯强度均达到饱和，超过该值后，接头的抗弯强度与胶粘剂的种类无关，接头的最大效率为96%。不同胶粘剂的拉伸强度略有不同，斜率为1.0的胶接效率最高，为84%。2)斜指接头的冲击弯曲吸收能量效率随坡度比的增大而增加，但除聚氨酯树脂外，其它胶粘剂的增加幅度较小。在斜率比为1.0的情况下，采用聚氨基甲酸酯的接头效率最高，为62%。我们研究了斜率和粘结剂对弯曲断裂过程中产生的声发射性能的影响。与间苯二酚酚醛树脂连接的接头在较低的载荷水平下开始产生声发射，而与环氧树脂连接的接头在约1/2载荷水平的断裂载荷下产生声发射事件。在间苯二酚、酚醛树脂和环氧树脂的引发下，聚氨酯接头的声发射发生介于两者之间。

1. To develop wood joint of high performance, we investigated the effect of slope ratio and adhesive on the performance of the sloped-finger joints whose bottoms of fingers were sloped. The adhesives used were resorcinol phenol formaldehyde resin, epoxy resin, and polyurethane resin. The slope ratios were o, 0.5, 1.0, 1.5, and 2.0. The performance of the sloped-finger joint was examined by static bending, impact bending, and tensile test. 1) The tensile strengths as well as the bending strengths of the joints were saturated at a slope ratio of 1.0, above which the bending strengths ded not depend upon the kind of adhesives and the maximum efficiency of the joint was 96%. There were slight differences in tensile strength among the abhesives, and the efficiency of the joint with a slope ratio of 1.0 and with polyurethane showed the maximum value of 84%. 2) The efficiencies of the absorbed energies in impact bending of the sloped-finger joints increased with an increase in slope ratio, but the extent of increase for adhesives except poly-urethane resin was small. The efficiency of the joint with a slope ratio of 1.0 and with poly-urethane showed the maximum value of 62%.2. We investigated the effect of slope ratio and adhesive on the properties of AE generated in the bending fracture process. The AE events of joint with resorcinol phenol formaldehyde resin began to be emitted at a low load level, whereas those of joint with epoxy resin did at about 1/2 load level of the breaking load. The initiation of AE generation of joint with polyurethane was intermediate between those with resorcinol phenol formaldehyde resin and with epoxy resin.