ADHESIVELY BONDED JOINTS are popular fastening systems for wood products andstructures. Fiber-reinforced p...

ABSTRACT: In this paper, the shear-mode (Mode-II) fracture toughness of wood– wood and wood–fiber reinforced plastic (FRP) bonded interfaces using unique linear tapered end-notched flexure (TENF) specimens is evaluated. A tapered beam on elastic foundation (TBEF) model developed for design and analysis of the TENF specimens is briefly introduced. Based on the TBEF model, the TENF specimens are designed to achieve an approximate constant compliance rate change for fracture tests, and design procedures for Mode-II fracture of bonded interface are accordingly developed. The linear compliance rate changes of the designed TENF specimens are verified experimentally by the compliance calibration tests and numerically by finite element modeling. Two types of TENF specimens, namely for wood–wood and wood–FRP bonded interfaces, are designed and tested to determine the fracture toughness values of adhesively bonded interfaces under Mode-II loading. The critical loads for crack initiation and arrest are measured during the testing, in which the critical strain energy release rates are then easily evaluated by making use of the approximate constant compliance rate change of the designed specimens over defined crack lengths. The wood–wood and wood–FRP bonded interfaces tested in this study exhibit a stable crack propagation behavior. The unique TENF specimen and experimental–design program presented in this paper can be efficiently used to evaluate the Model-II fracture toughness of hybrid material interface bonds, and the fracture toughness values obtained can be applied to detect the potential delamination and crack growth of the adhesively bonded joints