Short- and long-term performance of wood based panel products subjected to various stress modes

This paper presents the findings from comprehensive studies for enhancing efficiency and competitiveness of wood based panels for uses in furniture and other building construction industries. Five stress modes, which are encountered in the design and applications of wood based panels, were investigated, i.e. flat-bending, edgewise-bending, panel shear, planar shear and concentrated load stresses. Four commercial board types, namely plywood (PW), particleboard (PB), medium density fibreboard (MDF) and oriented strand board (OSB), were examined to evaluate the different responses to the various stresses. Results showed that stress modes had a significant effect on both short- and long-term performance of wood based panels: 1) wood based panels had a much higher capability to carry the stresses applied along the edge than plane of the panels, 2) the maximum failure load under planar shear was 10-16 times that under flat bending load and 2-3 times that under concentrated load, and the maximum failure load under panel shear was 3-9 times that under pure edgewise bending load, 3) for the materials tested, PW had a higher capability to carry both pure edgewise bending load and concentrated load, and MDF had a higher capability to carry pure flat bending load, and panel and planar shear load, 4) stress modes had a more significant effect on deflection under creep loading than short term test, with the ratio of deflection under flat bending, concentrated load and planar shear being 23:6:1 for PW under short term test, while 205:20:1 for PW and 507:72:1 for PB under creep loads, 5) theoretically calculated deflection was higher than the measured for short term tests but lower than the measured for creep tests, 6) the effect of stress modes on relative creep varied among the materials tested. These findings provide most constructive database for designing and using wood based panels in various industrial sectors.