Strength of corner and middle joints of upholstered furniture frames constructed with black locust and beech wood

Great interest is attracted lately in the utilization of Black locust (Robinia pseudoacacia L.) timber large quantities that are expected to be harvested and enter the market next years, since this species was included in the proposed and financed species for cultivation by the European Union. This study was carried out to evaluate the strength of the two most frequent joints in the upholstered furniture frames, constructed with black locust, using also beech wood (Fagus sylvatica L.) for comparative reason. In the specific research, the joints of mortise and tenon and double dowel were selected to be used and were constructed both in corner and middle joints, using two adhesives (PVAc and PUR). Bending moment capacity of the joint specimens was investigated, as well as the coefficient of elasticity of each joint.

Bending moment resistances of L-shaped furniture frame joints under tension and compression loadings

Effect of wood species, joint techniques, and adhesive type on bending moment resistances were investigated. 480 L-shaped joint specimens were tested including 2 loadings, 4 wood species, 3 joint techniques, 2 adhesives, and 10 replications. Specimens were prepared from Scotch pine, Oriental beech, oak, and chestnut. The joint techniques were dowel, half lap and open mortise and tenon, and type of adhesives were polyvinyl acetate (PVAc) and polyurethane (PU). Bending moment resistance of the joints under compression ranged from a low of 60 Nm for Scotch pine dowel joints with PVAc to oak half lap joints a high of 281 N.m w/PVAc. Bending moment resistance of the joints loaded in tension ranged from a low of 230 N.m for scotch pine dowel joints w/PVAc and to a maximum of 917 N.m for oak half lap joints w/PVAc. Highest average moment resistance was achieved with oak half lap jointed specimens w/PVAc, under both loadings.