Understanding the effect of weathering on adhesive bonds for wood composites using digital image correlation (DIC)

Abstract

Abstract The quality of wood composites is dependent on the bondlines’ performance and their moisture resistance. The effect of moisture intrusion into bondlines is the focus of this study. The strain profile in the bondline during loading was investigated and the effects of weathering on the bondline were quantified by digital image correlation (DIC), while load deflection data were collected from lap-shear tests (LShTs). A total of 75 LShTs were evaluated including four different adhesive types with Douglas-fir wood, out of which 39 served as controls and 36 as substrates for weathering. The effect of weathering on failure load was not statistically significant. Only the bonded surface and adhesive type have significant effects on failure load, as well as the three-way interaction between the bonded surface, adhesive, and weathering, as revealed by three-way analysis of variance (ANOVA). The average effective shear moduli for the weathered samples were significantly lower than those for the control samples.