Bending moment resistance of dowel corner joints in case-type furniture under diagonal compression load
We investigated bending moment resistance under diagonal compression load of corner doweled joints with plywood members. Joint members were made of 11-ply hardwood plywood of 19 mm thickness. Dowels were fabricated of Beech and Hornbeam species. Their diameters (6, 8 and 10 mm) and depths of penetration (9, 13 and 17 mm) in joint members were chosen variables in our experiment. By increasing the connector’s diameter from 6 to 8 mm, the bending moment resistance under diagonal compressive load was increased, while it decreased when the diameter was increased from 8 to 10 mm. The bending moment resistance under diagonal compressive load was increased by increasing the dowel’s depth of penetration. Joints made with dowels of Beech had higher resistance than dowels of Hornbeam. Highest resisting moment (45.18 N·m) was recorded for joints assembled with 8 mm Beech dowels penetrating 17 mm into joint members Lowest resisting moment (13.35 N·m) was recorded for joints assembled with 6 mm Hornbeam dowels and penetrating 9 mm into joint members.
Torsional strength of dowel joints constructed of plywood and oriented strandboard
The torsional strength of dowel joints is an important consideration in the design of furniture frames constructed of plywood and oriented strandboard (OSB) because several members, but especially the seat rails of sofa frames, may be subjected to substantial torsional forces. The torsional strength of two-pin dowel joints constructed of plywood and OSB was investigated in this study. Experimental results showed that when the dowel spacing and rail width increased, the torsional strength of the joints increased significantly, and this increase was linear with the dowel spacing or rail width. Specimens loaded in the flat position yielded significantly lower torsional strength values than specimens loaded in the edge position. Joints subjected to high torsional forces such as the front rail to stump joints in smooth-front sofas or the side rails in T-front sofas should be reinforced with glue blocks or gusset plates in order to develop the strength needed to resist in-service loads.
Gut immunity in Lepidopteran insects.
Lepidopteran insects constitute one of the largest fractions of animals on earth, but are considered pests in their relationship with man. Key to the success of this order of insects is its ability to digest food and absorb nutrition, which takes place in the midgut. Because environmental microorganisms can easily enter Lepidopteran guts during feeding, the innate immune response guards against pathogenic bacteria, virus and microsporidia that can be devoured with food. Gut immune responses are complicated by both resident gut microbiota and the surrounding peritrophic membrane and are distinct from immune responses in the body cavity, which depend on the function of the fat body and hemocytes. Due to their relevance to agricultural production, studies of Lepidopteran insect midgut and immunity are receiving more attention, and here we summarize gut structures and functions, and discuss how these confer immunity against different microorganisms. It is expected that increased knowledge of Lepidopteran gut immunity may be utilized for pest biological control in the future.