Fatigue Properties under Cyclic Non-Linear Deflection in Bending for Laminated Wood
Nakano Takato; Mototani Yuki
Abstract:Fatigue properties under cyclic non linear in bending were examined at room temperature for laminated wood with resorcinol resin adhesive (RF) and aqueous polymer isocyanate resin adhesive (API). The change of both the relative stress (s/s0) and temperature rising (DT) which was measured at the point of the maximum temperature rising depended upon mechanical properties of adhesives in a neutral layer of specimens. This is because, for laminated wood with API, an adhesive layer causes heating by cyclic deflection so that the stress in a neutral layer decreases, while, for RF, such heating does not cause. It was found that the peak of DT related to fatigue life. Both (s/s0)p and (s/s0)b are linear to the peak temperature DTp, and more the logarithmic cyclic number to failure, log Nb, is linear to the logarithmic cyclic number to the peak of DT, log Np. Key Words:laminated wood, fatigue failure, temperature rising, relative stress