Bending moment capacity of simple and haunched mortise and tenon furniture joints under tension and compression loads

A study was conducted to examine the effects of tenon geometry on the bending moment capacity of simple and haunched mortise and tenon joints under the action of both compressive and tensile loads. The effects of tenon width (25, 37.5, and 50 mm), tenon thickness (7.5, 10, and 15 mm), and tenon length (20, 25, and 30 mm) were examined. All of the joints were constructed of Turkish beech (Fagus orientalis Lipsky) and were assembled with a 40% solid-content polyvinyl acetate. Optimum results were obtained with joints constructed with 10-mm-thick tenons that were 37.5 mm wide by 30 mm long. Tenon length was found to have the greatest effect on joint capacity, whereas tenon width was found to have a much smaller effect. Joints constructed with 37.5-mm-wide haunched tenons had essentially the same moment capacity as joints constructed with 37.5-mm simple tenons. Optimum tenon width was 10 mm (1/3 of rail thickness); joints constructed with 10-mm-thick tenons had greater capacity than joints constructed with either 7.5- or 15-mm thick tenons.