| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1989: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1988: ¥800,000 (Direct Cost: ¥800,000)
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| Research Abstract |
Three-ply double lap shear specimens were prepared using beech wood as core. On both sides are solid wood (Buna and Akamatsu) and wood-based materials (plywood, particleboard,and fiberboard), Three types of joints were made, namely, glued joint using resorcinol and water soluble polyvinyl isocyanate as adhesives; nailed joint and nailed glue joint. Small and semi-large specimens of the same type were prepared. The former was and same type were prepared. treated with sea water and fresh water by vacuum soak-exposure method while the latter was subjected to sea hater soak-dry repeat exposure and exposure to the weather at sea side. After exposure the maximum load to failure of the specimen and the accumulated salt content were measured and data analyzed.
The durability of each type of joint (maximum load to failure) all decreaded compared to the unexposed ones. The decrease in strength is, more pronounced in the case of wood-based materials than in the solid wood. However, there is no significant differences between the salt water and fresh water treatment, between glue joint and nailed glue joint, and within different adhesives.
For semi-large specimen subjected to accelerated exposure, the wood- based materials exhibited higher deterioration than the solid counterpart. The joint strengths for specimen exposed outside and those that were subjected to 6-cycle accelerated exposure were compared. The results showed that the glued joint and the nailed-glue joint have about the same value. Lower values were obtained for the nailed joints exposed outside. The salt content of the specimen increase with the increase in the number of cycles. Inverse correlation between joint strength and the number of cycles were observed.
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