Strength and Stress of the Strapped Adhesive Joints made of Hinoki Cypress and Bamboo Plate under Tensile Loadings

In the present study, new high-performance strapped adhesive plates comprising of hinoki cypress (Chamaecyparis obtusa) and bamboo (Phyllostachys heterocycla) were investigated. Such plates are expected to find applications in making furniture or house wall construction. Two test set-up were performed, single-strap joint and double-strap joint. In the single-strap joint set-up, one bamboo plate was glued to one side of two abutting hinoki plates. Two thickness bamboo plate variables were tested, using 4 and 2 mm. On the other hand, in the double-strap joint set-up, two identical size bamboo plates were glued to both side of the two abutting plates. Two thickness bamboo plate variables were also tested, 4 and 2 mm. In all set-up, the hinoki plates were not bonded to each other. The joints were subjected to tensile strength tests until peeling, and the results were compared. In addition, the stress and strain were calculated using an elastic and orthotropic finite element method (FEM). It was found that the tensile load at rupture for a double-strap joint was not affected by the thickness of the bamboo plates. On the other hand, for a single-strap joint the thickness of the bamboo plates affects the tensile load at rupture. When the single-strap joint with thin bamboo plate was ruptured, the tensile load was larger than that of the more rigid thick bamboo plate. It was found that the stress around the adhesive layer of the joint with lower rigidity plate is smaller by flexibly deforming the bonded part under tensile loadings.