This project main aim was to increase knowledge on substrates and construction on a long term use. In this project, aging schedule was used to obtain accelerate aging. Aging was performed to generate fatigue in the products assessed. The assessment performed provides knowledge on the component used in the products. Substrates assessed were Russian plywood, HDF and OSB. The nature of the process used to obtain the surface layer was also evaluated. Slicing, peeling and sawing processes were used to obtain sugar maple wear layer on the EWF. Finally, cold set adhesive were used to bond the component. These adhesives were PVA type II, polyurethane, EPI and epoxy.
The prototypes were first studied in order to assess their performance before aging. The method used was systematic measurement trough indoor winter and summer conditioning. All parameters studied were significant. These parameters were type of adhesive, type of substrate, and the process used to obtain the surface component. Interactions between these parameters were also significant. The type of substrate was the heaviest parameter. Process used to obtain the surface component was also an important parameter.
Long term performance was also assessed. Aging cycle was determined in order to have dry condition at the end of each cycle to allow cupping measurement. The results of the ANOVA have shown heavy F value for the effect of aging cycles, type of substrate and the interaction of the substrate and the aging cycles. These numbers point out the substrate as the mean source of fatigue in the material. OSB prototypes have presented an increasing cupping deformation according to the number of aging cycle achieved.
For prototypes made with PVA, every substrate has generated significant different fatigue performance. Ranking was as follows: OSB with the high fatigue observed, followed by the HDF and the Russian plywood. Similar raking can be determined for surface component: sawn surface component with the highest fatigue observed, followed by peeled component and sliced component.
For the prototype made with epoxy observation are not as stable as for PVA. This was caused by wide variability of the measurement observed in the prototypes.
For the prototypes made with hot melt PU adhesive, fatigue performance ranking (order as previous) associate to surface component was sawn, sliced and peeled surface components. Taking into account substrate, ranking was OSB, HDF and Russian plywood.
Observations with EPI were the same as for PVA except that curves are closer and the maximum deformation observed were roughly 15-20% lower.
Aging of adhesive was specifically assessed. Aging cycle was similar to the one used for the aging of the prototypes. Shear strength was the criterion used to assess the adhesive. Both the type of adhesive and the aging cycle were highly significant as well as the interaction of these. Initially, all adhesives had similar shear strength but after 10 aging cycles, EPI, hot melt PU and PVA were similar and PU hot melt, PVA and PU liquid were also similar. In fact, EPI and liquid PU were different as they were respectively the best and the worst adhesive used.