Fracture behavior of laminated wood bonded with water based polymer-isocyanate resin and resorcinol-formaldehyde resin under impact fatigue

摘要

The impact fatigue behavior of laminated wood bonded with water based polymer-isocyanate resin (WPI) and resorcinol-formaldehyde resin (RF) was investigated. The number of cyclic blows to failure (N-b) for laminated wood was lower than that for solid wood. For laminated wood, Nb showed a significant decrease with an increase in temperature, while for solid wood, it showed a slight decrease. The fatigue life of laminated wood bonded with WPI was lower than that of RE For laminated wood bonded with WPI, the ratio of the height of rebound (Q(n)) to that of the first rise (P-n), which was evaluated from an impact stress wave, remained constant and then gradually decreased before failure. This indicates that the energy consumed by heating increased before failure because the cured WPI has viscosity. For RF, Q(n)/P-n remained constant immediately before failure because cured RF is rigid. At a lower test temperature, the fracture surface almost entirely comprised the wood. As the temperature increased, the laminated wood fractured predominately in the adhesive layer. This could be attributed to a decrease in the rigidities of WPI and RE The impact fatigue behavior of laminated wood is related to the mechanical properties of the adhesives. (C) 2008 Wiley Periodicals, Inc.