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A theoretical model developed for predicting nail withdrawal load from wood by mechanics

Wang, Yiren, Lee, Shih-Hao
European journal of wood and wood products 2018 v.76 no.3 pp. 973-978
friction, microstructure, models, prediction, statistical analysis, wood, wood anatomy, wood construction
Assembling wood structure involves fastenings in jointing wood members. The strength and stability of wood structure strongly depend on these fastenings that hold wood members together. Nails are one of the most common mechanical fastenings used in wood construction. Wood is a cellular and orthotropic bio-material. For utmost rigidity, strength, and service of wood-nailed joint, the nail requires joint designs adapted to the maximum strength properties of wood along and across the grain. The traditional model for prediction of withdrawal load of nails driven into side grain of wood was purely empirical, which was built on a statistical approach. A model based on the Coulomb’s friction law, the contact pressure of interference fit, Hankinson’s off-axis baring strength, and assumed honeycomb microstructure of wood cell was proposed and validated. When compared with experimental data of nail withdrawal load, this model not only showed better prediction of nail withdrawal load than the traditional model but also bears a physical meaning.