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PL
Artykuł przedstawia badania wstępne dotyczące wielowarstwowego materiału kompozytowego spełniającego postawione wymagania dotyczące budowy kadłubów wybranych jednostek pływających, przeznaczonych do żeglugi śródlądowej. Dokonano analizy i opisano warunki eksploatacyjne jednostek pływających śródlądowych, ze szczególnym naciskiem na bezpieczeństwo i koszty obsługi eksploatacyjnej jednostek. Zaproponowano sposób zwiększenia bezpieczeństwa użytkowania jednostki przez wprowadzenie wielowarstwowego materiału ograniczającego możliwości rozszczelnienia kadłuba w przypadku uderzenia o obiekty znajdujące się pod wodą. W celu badań porównawczych określono warunki przyjętej technologicznej próby zginania oraz wymagania dotyczące wielowarstwowych płyt próbnych. Wytworzono trój- i czterowarstwowe płyty próbne o grubości 14-30 mm, wykorzystując: kompozyty zawiesinowe na bazie żywicy epoksydowej zbrojone cząstkami ceramicznymi, kompozyty na bazie żywicy poliestrowej zbrojone uporządkowanym włóknem szklanym oraz piany metalowe na bazie aluminium oraz kompozytu aluminiowo-ceramicznego. Przedstawiono wyniki wstępnych badań dotyczących odporności płyt próbnych na zginanie w warunkach przyjętej próby technologicznej, a także odporności na ścieranie. Odniesiono się do możliwości wytwarzania tak skomponowanych materiałów warstwowych w warunkach znanej, szeroko stosowanej technologii formowania elementów kształtowych z kompozytów polimerowo-szklanych w formach negatywowych. Doprecyzowano typ śródlądowych obiektów pływających, wykazując zalety i celowość stosowania tych materiałów.
EN
The article presents the preliminary tests of a multilayer composite material that meets design requirements for hulls of some vessels intended for inland navigation. In the analysis and description of operating conditions of inland vessels a particular focus was put on the safety and operational costs of the vessels. The solution proposed to increase operational safety consists in introducing a multilayer material that limits the loss of hull integrity in the case a vessel hits an underwater object. For comparative studies, the conditions of the adopted technological bending test were defined along with requirements for multilayer test plates. Plates produced for the tests were three- and four-layered 14-30 mm thick plates made of three materials: epoxy resin-based suspension composites reinforced with ceramic particles, polyester resin-based composites reinforced with ordered fiberglass and metal foams based on aluminium and aluminium-ceramic epoxy. The preliminary research results include the resistanceof test plates to bending in the adopted technological test conditions and abrasive resistance. Particular reference was made to the manufacturing of so composed layered materials applying a known and widely used process of forming profiled elements of polymer-glass composites in negative moulds. The type of inland vessel was more precisely indicated, along with advantages and purpose of using the materials under consideration.
EN
In the present study, a CFD simulation of forced convection in a rectangular block of aluminum foam is investigated. A two energy equations model with the Brinkman-Forchheimer extended Darcy model is considered in the CFD investigation. The governing equations are solved using COMSOL, a commercial multiphysics finite-element PDE solver. Three types of aluminum foam 10-, 20-, 40- pore per inch with different porosity are studied. A parametric study for the range of Reynolds number Re = 250-2000 and the imposed heat flux qw = 0:8−1:6 (W/cm2) is carried out to examine the thermal and the fluid flow behaviors of the aluminum foams. It is found that the plug flow conditions are prevalence for the aluminum foams. The 40-pore per inch aluminum foam has a better heat transfer performance with a larger pressure drop, followed by the 20-, and then by the 10- pore per inch. The validation of the simulation results is made against experimental data from the literature and showed a perfect agreement.
EN
An aluminum foam added with foaming agent, is classified into an open-cell type for heat transfer and a closed-cell type for shock absorption. This study investigates the characteristic on the torsion of aluminum foam for a closed-cell type under impact. The fracture characteristics are investigated through the composite of five types of aluminum foam (the thicknesses of 25, 35, 45, 55 and 65 mm), when applying the torsional moment of impact energy on the junction of a porous structure attached by an adhesive. When applying the impact energy of 100, 200 and 300J, the aluminum foams with thicknesses of 25 mm and 35 mm broke off under all conditions. For the energy over 200J, aluminums thicker than 55 mm continued to be attached. Furthermore, the aluminum specimens with thicknesses of 55 mm and 65 mm that were attached with more than 30% of bonding interface remained, proving that they could maintain bonding interface against impact energy. By comparing the data based on the analysis and test result, an increase in the thickness of specimen leads to the plastic deformation as the stress at the top and bottom of bonding interface moves to the middle by spreading the stress horizontally. Based on this fracture characteristic, this study can provide the data on the destruction and separation of bonding interface and may contribute to the safety design.
EN
The crash box between a bumper and a car body in automobiles can reduce impacts for car bodies with a bumper at a low-speed collision by preventing the shocks. Also, this crash box is the part playing a very important role for the safety of vehicle and the reduction of repair cost, and many studies have been investigated for the performance. In this study, aluminum foam was inserted in an aluminum crash box to analyze the relationships of deformation, stress and internal energy. The compression characteristics are compared with six cases. In addition, the load due to displacement at experiment for a case is verified by modeling with finite elements and performing the structural analysis. As these study results for investigating characteristics of the crash box, it is thought that the effective designs of crash box to enhance the durability for collision are made possible.
EN
This paper studies the characteristics of junction structure of closed-cell type aluminum foam, which is generally used as a shock absorber. TDCB specimens were designed for mode III type with thickness as a variable and performed a fatigue experiment on them by thickness. As the result, the load value of all specimens peaks under 0 to 25 cycles and decreases as the cycles increase. As the specimen thickens by 10 mm, the maximum load value is 1.2 times. When the thickness increases by 20 mm, the maximum value increases by 1.5 times. This study result can be utilized by investigating the mechanical characteristics of TDCB specimens for mode III type under fatigue loading conditions systematically and efficiently.
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PL
Przedstawiono istotne zagadnienia dotyczące stosowania wysokociśnieniowej strugi wodno-ściernej do kształtowania struktur materiałowych typu plaster miodu oraz spienione aluminium, które są używane w konstrukcjach lotniczych. Zastosowana metoda pozwala na jednozabiegowe wycinanie przestrzennych półfabrykatów o poosiowo zmiennych kształtach poligonalnych. Zaprezentowane efekty kształtowania takich obiektów oraz wyniki badań (SEM, SGP) jakości obrobionej powierzchni uprawniają do pozytywnej oceny przydatności tej metody obróbkowej.
EN
The paper presents important issues of high-pressure abrasive-water jet cutting of materials’ structures shaping (e.g. honeycomb and aluminum foam), which are used in aircraft constructions. The applied method allows the spatial single cutting of semi-finished products of axially variable polygonal shapes. Presented effects of such objects’ forming, as well as the results of the quality of the machined surface (SEM and SGP), allow for a positive assessment of the usefulness of such a method of machining.
EN
An image processing technique was used to model the internal structure of aluminum foam in finite element analysis in order to predict the compressive behavior of the material. Finite element analysis and experimental tests were performed on aluminum foam with densities of 0.2, 0.25, and 0.3 g/cm3. It was found that although the compressive strength predicted from the finite element analysis was higher than that determined experimentally, the predicted compressive stress-strain curves exhibited a tendency similar to those determined from experiments for both densities. However, the behavior of the predicted compressive stress-strain curves was different from the experimental one as the applied strain increased. The difference between predicted and experimental stress-strain curves in a high strain range was due to contact between broken aluminum foam walls by the large deformation.
8
Content available remote Struktury przepływu gaz-ciecz w kanałach wypełnionych pianami aluminiowymi
PL
Przedstawiono wyniki badań doświadczalnych dotyczących identyfikacji struktur przepływu dwufazowego gaz-ciecz w kanałach wypełnionych pianami aluminiowymi. W trakcie badań obserwowano struktury korkową, rzutową, tłokową i rozwarstwioną. Stwierdzono, że rodzaj struktur przepływu gaz-ciecz zależy od warunków przepływu, przy czym nie odnotowano wpływu parametrów geometrycznych pian na rodzaj przepływu. Warunki występowania poszczególnych struktur przepływu mogą być w przybliżeniu określone za pomocą mapy przepływu Bakera, opracowanej dla kanałów bez wypełnienia.
EN
The paper presents results of experimental studies on flow patterns identification in gas – liquid two-phase flow through channels filled with aluminum foams. During the experiments plug, semi-slug, slug, and stratified flow patterns were observed. It was found that a type of gas – liquid flow pattern depended on flow conditions, while there was no effect of foam geometric parameters on a flow type. The occurrence and conditions of particular flow patterns can be roughly determined using the Baker flow regime map developed for horizontal tubes without filling.
PL
Opisano wyniki badań hydrodynamiki przepływu jedno i dwu-fazowego powietrze-woda oraz powietrze-olej przez kanały wypełnione pianami aluminiowymi o komórkach otwartych. Stwierdzono, że pory przepływu płynu przez piany metalowe, poza wpływem prędkości i właściwości płynu, zależą od porowatości pian, wielkości komórek oraz kształtu szkieletu komórkowego. W przypadku przepływu dwufazowego znaczną rolę odgrywają również struktury przepływu. Zmianom struktur przepływu często towarzyszą gwałtowne, sięgające kilkudziesięciu procent zmiany wartości oporów przepływu.
EN
The paper describes the research results of hydrodynamics of air-water and air-oil two-phase flow through channels filled with open-cell aluminum foams. It was found that flow resistance of fluid through metal foams, beyond the obvious influence of velocity and fluid properties, depends on foam porosity, size of cells and shape of cell skeleton. In the case of two-phase flow, flow patterns also play a significant role. Flow pattern changes are often accompanied by sharp, reaching several tens of percents, changes in flow resistance.
EN
Cellular materials have found wide-spread attention in structural applications involving impact energy absorption. The choice of the most suitable density of a cellular material, for a particular impact application, is based on its mechanical response, which may be obtained through experimental tests and/or models. A current study is focused on prediction of a mechanical response of a wide range of densities of a cellular material using available experimental data of very few densities. Best fitting-parameters of four selected phenomenological models, to fit the available experimental response of three distinct aluminum foam densities, are evaluated. The relationship between the best-fitting parameters and density of the foam is established by using two types of functions. The first function is based on a power law relationship between each parameter and foam density ρ, while the second function assumes each parameter as a linear combination of ρn and ρ, where n is any real number. The former function is found reasonable in the cases of both parameter interpolation and extrapolation while the latter is found reasonable for a parameter interpolation only. The findings of a current study emphasize for a conscious approach during selection of density dependent laws for phenomenological model parameters to avoid any erroneous or misleading design decision.
EN
This paper analyses the experimental findings within heat transfer when heating up air, water and oil streams which are passed through a duct with internal structural packing elements in the form of metal foams. Three types of aluminum foams with different cell sizes, porosity specifications and thermal conductivities were used in the study. The test data were collected and they made it possible to establish the effect of the foam geometry, properties of fluids and flow hydrodynamic conditions on the convective heat transfer process from the heating surface to the fluid flowing by (wetting) that surface. The foam was found to be involved in heat transfer to a limited extent only. Heat is predominantly transferred directly from the duct wall to a fluid, and intensity of convective heat transfer is controlled by the wall effects. The influence of foam structural parameters, like cell size and/or porosity, becomes more clearly apparent under laminar flow conditions.
EN
It is indispensable to evaluate fracture energy as the bonding strength of adhesive at composite material with aluminum foam. This specimen is designed with tapered double cantilever beam by British standards (BS 7991 and ISO 11343). 4 kinds of specimens due to m values of 2, 2.5, 3 and 3.5 are manufactured and compared each other with the experimental results. Adhesive fracture energy is calculated from the formulae of British standards. The value of m is the gradient which is denoted as the length and the height of specimen. As m becomes greater at static experimental result, the maximum load becomes higher and the displacement becomes lower. And the critical fracture energy becomes higher. As m becomes less at fatigue experimental result, the displacement becomes higher and the critical fracture energy becomes higher. Fracture behavior of adhesive can be analyzed by this study and these experimental results can be applied into real field effectively. The stability on TDCB structure bonded with aluminum foam composite can be predicted by use of this experimental result. Adhesive fracture energy is calculated from the formulae of British standards. Based on correlations obtained in this study, the fracture behavior of bonded material would possibly be analyzed and aluminum foam material bonded with adhesive would be applied to a composite structure in various fields, thereby analyzing the mechanical and fracture characteristic of the material.
PL
W artykule przedstawiono przykład rozwiązania konstrukcji złącza klejowego piany aluminiowej wykonanego przy użyciu dwuskładnikowego kleju epoksydowego. Sformułowano założenia dla złącza dotyczące rozkładu sił i naprężeń w rozciąganej próbce. Ustalono zalecenia do przygotowania powierzchni pian, procedurę klejenia uwzględniającą kontrolę porowatości piany i chropowatości klejonej powierzchni blachy. W wyniku badań wytrzymałościowych określono mechanizm niszczenia złącza. Zaproponowano optymalizację konstrukcji złącza poprawiającą jego właściwości.
EN
The paper presents an example of design solution of aluminum foam glue joint using two-component epoxy glue. The joint principles for distribution forces and stresses in the tensile sample were formulated. Recommendations for surface preparation of foam and gluing procedure aimed at control the porosity of the foam and glued surface roughness were established. As a result of strength tests defined joint destruction mechanism was proposed. It was suggested that optimized joint design improving its properties.
EN
In this paper, effects of changeable transverse and longitudinal pitches and porous media inserts on overall heat transfer from an elliptic tube bundle are studied numerically. Go- verning equations used for the analysis of fluid flow inside the porous media inserts are Darcy-Brinkman-Forchheimer equations, and for the fluid flow without porous inserts are classical Navier-Stokes equations. A finite volume code is used to solve the governing equ- ations. The tube bundle consists of 10 rows of elliptical tubes 3.17 cm in major diameter and 1.4 cm in minor diameter in a staggered arrangement. Aluminum foams are used as porous media inserts between the tubes with three different porosities. It is shown that the use of the aluminum foam enhances heat transfer significantly (more than 50% in some cases). However, the pressure drop increases as the Reynolds number grows. The differences among various cases are also discussed. Finally, it is shown that the overall heat transfer efficiency increases more effectively by increasing the transverse pitch with respect to the longitudinal and diagonal pitches while the flow regime remains laminar.
EN
Metallic foams are materials that are subject of an ongoing research with the broad applicability in many different areas (e.g. automotive industry, building industry, medicine, etc.). These metal materials contain in their structure artificially created pores. These pores give them specific properties, such as: large rigidity at low density, high thermal conductivity, capability to absorb energy, etc. Since the discovery of porous metallic materials numerous methods of production have been developed. The aim of the paper is to introduce effective casting methods of manufacturing of metallic foams, namely cast metal filters from the aluminum alloy. Research deals with investment casting with use of pattern made of polymeric foam, which is used for production of metallic foam with open pores. The main disadvantage of this procedure consists in removing the mould material without damaging the fine structure of the cast filter. Plaster is used as the mould material and the most important result of this paper is the presentation of the effective procedure of plaster removal from the porous structure of cast filters.
PL
Piany metalowe są przedmiotem wielu badań gdyż znajdują szerokie zastosowanie w wielu dziedzinach np. produkcji samochodów. budownictwie czy w medycynie. W swojej strukturze zawierają sztucznie wytworzone pory, zapewniające uzyskanie specyficznych właściwości jak duża wytrzymałość, niewielka gęstość, wysokie przewodnictwo cieplne zdolność do absorpcji energii itp. Od czasu wynalezienia porowatych materiałów metalowych opracowano wiele metod ich wytwarzania. Celem opracowania jest wprowadzenie efektywnych metod odlewniczych produkcji pian metalowych, szczególnie ze stopów glinu. Studium zajmuje się precyzyjną metodą odlewania przy zastosowaniu modelu wykonanego z piany polimerowej stosowanej w produkcji piany z otwartymi porami. Główna niedogodność metody polega na trudności usuwania materiału formierskiego, bez naruszenia delikatnej struktury odlewanego filtra. Jako materiał formierski stosuje się gips i najważniejszym wynikiem pracy jest przedstawienie efektywnej procedury usuwania gipsu z porowatej struktury odlanego filtra.
16
PL
W pracy przedstawiono wyniki badań doświadczalnych dotyczących przepływu powietrza oraz wody przez piany aluminiowe o komórkach otwartych. Analiza wyników badań pozwoliła określić wpływ parametrów piany na wartość strat ciśnienia przy przepływie płynu przez przestrzeń komórkową pian. Stwierdzono, że opory przepływu płynu przez piany aluminiowe można opisać równaniem Forchheimera. Wykazano również, że przepuszczalność pian jak i współczynnik inercji są wielkościami zależnymi nie tylko od parametrów strukturalnych pian, ale również od warunków przepływu i właściwości płynu.
EN
The paper presents experimental results concerning air and water flow through open-cell aluminum foam. Analysis of the results allowed one to determine the influence of foam parameters on pressure loss values in fluid flow through the cellular space of foams. It was found that frictional pressure drop of fluid flowing through aluminum foam could be described by the Forchheimer equation. It was also demonstrated that permeability of foams as well as inertia coefficient are not only dependent on structural parameters of foam but also on flow conditions and fluid properties.
17
Content available remote Global stability of an aluminum foam stand-alone energy absorber
EN
Aluminum alloy foam is the commonly used material in energy absorber design due to its excellent ability to dissipate energy in relation to density. This paper investigates the behavior of standalone absorber made of ALPORAS aluminum foam. The limiting parameters in the aforementioned application are the stability of absorber column and the risk of global buckling. Specimens with different slenderness ratio were crushed in order to find the transition point between local collapse of the cell walls and global buckling of the entire column. The ability of the aluminum foam energy absorber to work even after partial global buckling was presented.
18
Content available remote Preparation of Aluminium Foam Edges for Welding
EN
This paper presents the results of cutting aluminum foams. The experiment includes the following mechanical methods of cutting: circular saw cutting, band-saw cutting, EDM cutting, water-jet cutting, and thermal cutting methods: laser cutting and air plasma cutting. The influence of the cutting method on the edge geometry was specified in the paper. EDM was defined as the most advantageous method of Al foam cutting, as providing the best aluminium foam edges surface quality for welding.
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