Pullout Resistance of Densified Wood Dowel Welded by Rotation Friction

Rotation welding is a novel technique to produce structurally efficient wood joints without any synthetic adhesives, in which wooden dowels are inserted into timber members by high-speed rotation to form the bonding interface layer. This assembly technique is usually used for furniture, but the relatively short inserted dowel length restricts its structural applications due to the lack of molten materials from dowels and the fracture of dowels. Densified wood can be more suitably used as wooden dowel materials, which can provide more molten materials and higher mechanical properties. This study presents the experimental results on densified wood dowels welded in glulam substrate. The effect of the main parameters on the pullout resistance was analyzed, such as the ratio of the diameter of the wooden dowel to the diameter of the predrilled hole in the substrate, the depth of the predrilled hole, the insertion direction, and dowel materials. The welded joints made with densified wood dowels show higher pullout resistance than those with natural wood dowels reported in the literature. The diameter ratio of the dowel to the hole (12/9) can be optimized to yield better pullout resistance, and a longer inserted dowel length can be realized without a fracture of the dowels. The main difference with respect to the insertion direction is the optimum depth of the hole.