Effect of Glue-line Flexibility on Cleavage Fracture Toughness of Wood-Epoxy Resin Bond System

この論文は国立情報学研究所の学術雑誌公開支援事業により電子化されました。The paper concerns with effect of the mechanical properties of glue-line on the cleavage fracture toughness of wood-epoxy resin bond systems. Tensile stress-strain relations of the resin films flexibilized with polysulfide in various grades were tested at a range of head speed 0.09 mm/min to 180 mm/min and temperature 20℃ to 60℃. Resins containing 20 to 40 parts per hundred of resin (phr) behaved like elasto-plastic material and that of 60 phr like rubber. Numerical analysis of stress distribution in cleavage fracture toughness test specimens of wood-flexibilized epoxy resin bond system was made by using the values of mechanical properties of resin films obtained above. Less stress concentration was found on the tip of a crack in thicker and more flexible glue-line. Higher stress concentration was found on thinner and more rigid glue-line arid on lower density adherend. Test results on cleavage fracture toughness G_ of wood-epoxy resin bond specimens showed clearly that increasing flexibility and thickness of glue-line could effectively improve cleavage fracture toughness of wood-glue bond system