Effects of density profile of MDF on stiffness and strength of nailed joints

Abstract

Nail-head pull-through, lateral nail resistance, and single shear nailed joint tests were conducted on medium density fiberboard (MDF) with different density profiles, and the relations between the results of these tests and the density profiles of MDF were investigated. The maximum load of nail-head pull-through and the maximum load of nailed joints were little affected by the density profile. However, the ultimate strength of lateral nail resistance, the stiffness, and the yield strength of nailed joints were affected by the density profile of MDF and showed high values when the surface layer of the MDF had high density. It is known that bending performance is also influenced by density profile. Therefore, the stiffness and the yield strength of nailed joints were compared with the bending performance of MDF. The stiffness of nailed joints was positively correlated with the modulus of elasticity (MOE); in the case of CN65 nails, the initial stiffness of joints changed little in response to changes in MOE. The yield strength of nailed joints had a high positive correlation with the modulus of rupture (MOR). The stiffness and the yield strength of nailed joints showed linear relationships with MOE and MOR, respectively

Adhesives from Waste Protein Biomass for Oriented Strand Board Composites: Development and Performance

“…The profile over the different zones of the thickness resembled a symmetric “m‐shape,” with peak densities appearing near the board top and bottom surfaces (zones 1 and 3), and the lowest density in the core region (zone 2). Similar observations of higher surface and lower core density using commercial adhesives are extensively reported in the literature . The presence of this vertical density gradient is known to result in higher bending strength, but lower internal bond strength .…”

Randomly Oriented Strand Board Composites from Nanoengineered Protein-Based Wood Adhesive

“…Vertical density profile of ROSB panels prepared with CPA adhesives also showed similar density variations as compared to typical composite panels, where it showed a symmetric "M" shape with a higher density in two surfaces of the panels, and a low density in the panel core. 42,43 The presence of density profile is beneficial in improving the bending strength (MOE) of the composite panel. However, a very low density core has a detrimental effect on the internal bond strength of OSB panels.…”

Shear resistance for lateral force of light-frame wall sheathed with structural particleboard (PB)

“…It was considered that the shear strength of structural PB was high because of higher density of structural PB. It was reported that the properties of nail joint shear were proportional to density of members (Smith et al 2001;Sawata et al 2008;Sandhaas and Görlacher 2018). Therefore, the entire shear strength of wall might increase because the shear property of the nail joint used in structural PB will be high.…”

“…In contrast, the shear modulus of structural PB light-frame shear wall was lower than that of OSB light-frame shear wall. There was a positive relationship between the density of the wood-based material's surface layer and the nail joint's stiffness (Sawata et al 2008). Therefore, additional research might be needed to increase the shear modulus of structural PB walls considering the stiffness of the nail joint.…”