Fatigue Properties under Cyclic Non-Linear Deflection in Bending for Laminated Wood

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 (σ/σ₀) and temperature rising (ΔT) 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 ΔT related to fatigue life. Both (σ/σ₀)_p and (σ/σ₀)_b are linear to the peak temperature ΔT_p, and more the logarithmic cyclic number to failure, logN_b, is linear to the logarithmic cyclic number to the peak of ΔT, logN_p.