In this paper, the elastic behaviour in bending of three-layer plywood cantilever beams is analysed. Deflections of straight and half-circle cantilevers, loaded with a force at free end is determined experimentally and calculated using analytical and finite element method approach. The analytical calculation of deflection for the strait cantilever is obtained using a transformed cross section. The deflection of half-circle cantilever is determined by the classical laminated plate theory and Castigliano’s theorem. Loads and cantilever dimensions are varied in the study using the design of experiment. The deflection regression models for straight and semicircular plywood cantilevers are obtained from the experimental results. Analytically and numerically determined deflections of strait and half-circle cantilevers show very good agreement. Experimentally recorded deflections are approximately 30 % higher than analytical values. Stiffness properties and deflection values are influenced by direction of fibres in the outer layers of a three-layer plywood beam.

Aluminum alloys are widely used in military and aviation industry due to their properties such as low density and high strength. During the aircraft operation there are mechanical failures of various structural components caused by numerous mechanisms such as corrosion, material defects, high cycle fatigue and the like. One of the frequent mechanical failures on air-cooled piston engines is the cylinder head cracking. This paper is the continuation a comprehensive research of the Lycoming IO-360-B1F aircraft cylinder head failure. The failure of this type has already occurred during flight and about 50 failures like this have been registered from around the world, some of them with a fatal outcome and therefore require detailed research. The paper consists of machining of the tested specimens and their testing at many different locations and in many different laboratories throughout Bosnia and Herzegovina, Serbia and Slovenia. This paper is based on a research that includes the experimental analysis of mechanical properties of Aluminum alloy 242.0 which is a constituent material of the cylinder head of the Lycoming IO-360-B1F aircraft engine on which a crack appeared. Based on chemical, metallographic, static and dynamic experimental tests of the material properties, Aluminum alloy 242.0 static and fatigue properties were obtained, S-N curve was formed and endurance limit was determined. Results of numerical simulations of experiments, confirmed by experimental results, were performed to make numerical procedures reliable due to further research. The results of the research are planned to be implemented in numerical modeling of the cylinder assembly stress-strain state under workload and in further numerical research of Lycoming IO-360-B1F cylinder assembly integrity assessment.

3D printing technology is leading to great advancements and expanding the limits in many engineering fields and education. Geometrical accuracy of the parts produced by 3D printing could be a very important characteristic for some purposes. In this paper the geometrical accuracy of parts produced by FDM (Fused Deposition Modelling) 3D printing technology is investigated. For this purpose a benchmark part is designed and size, form, orientation and location accuracy of different features on it are evaluated using coordinate measuring machine. Two different FDM desktop 3D printers are used for the benchmark part printing.

Pokusi delaminacije s grednim uzorcima se cesto koriste kod ispitivanja razlicitih suvremenih materijala sa slojevitom strukturom, i kod razlicitih vrsta ovih pokusa javljaju se i razliciti nacini loma (otvaranja pukotine). Kod pokusa s mjesovitim nacinom loma znacajno je s aspekta dizajna napraviti podjelu energije loma na udjele od razlicitih nacina loma, tj. odrediti mjesovitost nacina loma. Problematika podjele energije loma u pokusima delaminacije s grednim uzorcima je predmet velikog broja istraživanja u posljednjih tridesetak godina i kao rezultat toga predložena su razlicita rjesenja zasnovana na analitickim i numerickim metodama. Rezultati dobiveni primjenom ovih rjesenja pokazuju dobro slaganje kod primjene na pokuse sa simetricnom geometrijom uzoraka, međutim, kod primjene na pokuse s asimetricnom geometrijom uzorka pokazuju znacajno neslaganje. U ovom radu je dat osvrt na odabrana analiticka i numericka rjesenja koja se mogu primijeniti za podjelu energije loma. Razmatrane su dvije pionirske, suprotstavljene teorije, prema Williamsu i prema Hutchinsonu i Suou, te nedavno predložena, poluanaliticka, SACA metoda, koja je s novim pristupom problemu objedinila ove dvije teorije. Rezultati primjene spomenutih metoda su na primjeru pokusa delaminacije s dvostrukim grednim uzorkom, kome je jedan krak opterecen momentom savijanja, uspoređene s rezultatima odabranih numerickih istraživanja zasnovanih na primjeni modela kohezivne zone.