Bending moment of mortise-and-tenon joints in a crossed chair base. : [Moment savijanja spojeva s čepom i rupom na križnoj potkonstrukciji sjedala stolice]

This paper investigated the bending moment of chair base joints. The ultimate bending moments (maximum moment), calculated on the base of the measured maximum applied loads (maximum force), were compared for the front leg and rear leg joints of a chair base. The joints had different angles between the stretcher and the leg (joint angle) as well different tenon lengths (30 mm and 32 mm). The results of the tests indicated that for different test specimen configurations but the same tenon-and-mortise geometry, the maximum force of joints with a smaller value of joint angle (front leg joints) was higher than the force values of joints with a larger angle (rear leg joints) for all tenon lengths. However, the results showed less difference among the calculated bending moments of the analysed sets of joints. A significant difference was not revealed between the bending moments of joints with a smaller value of joint angle and the bending moments of joints with a larger angle for all tenon lengths. A significant difference between the bending moments for the tenon length of 30 mm and tenon length of 32 mm was determined for rear leg joints but not for front leg joints. The presented approach of joint strength analysis through the testing of specimens with different shapes and dimensions are applicable to research and practice. U radu je proučavan moment savijanja spojeva na križnoj potkonstrukciji sjedala stolice. Krajnji momenti savijanja (najveći moment), izračunani na temelju izmjerenih najvećih opterećenja (najveća sila), uspoređeni su za spojeve prednjih i stražnjih nogu križne potkonstrukcije sjedala stolice. Spojevi su imali različite kutove između poveznika i noge (kut spoja), kao i različitu duljinu čepova (30 i 32 mm). Rezultati ispitivanja pokazali su da je za različitu konfiguraciju ispitnih uzoraka, ali za istu geometriju čepa i rupe, najveća sila bila veća za spojeve s manjim kutom (spojevi prednjih nogu) nego za spojeve s većim kutom (spojevi stražnjih nogu), i to za čepove obiju duljina. Rezultati su također pokazali manju razliku između izračunanih momenata savijanja analiziranih grupa spojeva. Nije utvrđena značajna razlika momenata savijanja spojeva s manjim i većim kutom za čepove obiju duljina. Značajna razlika između momenata savijanja za čepove dužine 30 i 32 mm utvrđena je za spojeve stražnjih nogu, ali ne i za spojeve prednjih nogu stolice. Prikazani pristup analize čvrstoće spojeva ispitivanjem uzoraka različitih oblika i dimenzija primjenjiv je u istraživanju i u praksi.Validerad;2023;Nivå 2;2023-04-17 (hanlid)</p

Physical and Mechanical Properties of a New Bio-Composite Material Based on Seashells for Use in Furniture Making

This paper explores the possibility of using recycled seashells from marine coasts of the Mali Ston Bay in Dubrovnik-Neretva County, Croatia, to create a novel bio material derived from waste seashells. In this research, two types of waste seashells, mussel (Mytilus galloprovincialis) and oyster (Ostrea edulis), combined with natural, non-toxic binders (bone glue) were investigated experimentally. The goal is to develop a sustainable material, suitable for the production of furniture and decorative objects. The parameters studied, included physical and mechanical properties of this material. The results showed that this bio composite material, derived from recycled seashells, is hygroscopic and has low compression strength. It should be used for making furniture components that don't bear heavy loads and it is suitable only for interior applications. This study presents an eco-friendly and sustainable material option, while optimizing the recycling of food waste materials