Manufacturing of B4C particle reinforced A360 aluminium cellular composite materials by the integration of stir casting and space holder methods

Stir casting method has become prominent for fabrication of metal matrix composites in recent years. This method can be adjusted for casting around space holding particles to obtain cellular composite materials. In this study, a specific method which is a combination of stir casting and space holder techniques were used to produce open-celled A360 aluminium-B4C composite foams with regular sized and distributed pores. Weight ratios of reinforcement particles determined as 0.5, 1, 1.5 and 2%. The influences of particle reinforcement on the microstructure and the mechanical behaviour of composite foams were investigated. Microstructures were analysed with optical microscope (OM), scanning electron microscope (SEM). Compression and hardness tests were carried out to observe the effects of reinforcement on mechanical properties. Compression strength properties and hardness of composites increased with the ceramic reinforcement, however the plastic strength of the composite foams showed worsening trend after a certain reinforcement ratio (0.5 wt.%). Energy absorption properties of the composite foams showed parallel trends with compressive strength properties.

Study of a highly porous composite material based on an aluminum matrix with an ordered cellular structure formed by hollow copper-graphite spherical granules

The structure and properties of a highly porous cellular composite material based on a framework of hollow spherical granules with a thin copper-graphite coating impregnated with an aluminum alloy have been investigated. Highly porous composite composite casting with molten form, filled with expanded polystyrene spherical granules with a thin copper-graphite layer applied to their surface. When the polymer core of the granules burns out in the casting, a highly porous cellular composite material is formed with an aluminum matrix filled with spherical pores ∅ 4 – 8 mm, adjoining the metal matrices through a thin (300 – 500 μm) copper shell. The density of the porous composite material obtained in this way is 1.67 g/cm3. In order to fill the space between the granules with aluminum melt, their surfaces were coated with a thin layer of titanium, molybdenum, or chromium borides, which positively affected the strength characteristics of the composite material as a whole. Estimated calculation of the shock absorber index of a new highly porous structural material based on aluminum matrices with a cellular structure made of spherical hollow granules regularly distributed over the volume proved the prospects of its subsequent use as an absorber of shock energy in shock-absorbing devices.

Simplified design method and parametric study of composite cellular beam

Nowadays, with the development of cutting and welding technologies, steel beams with regular circular openings, called cellular beams, have been widely used for construction. The cellular beams could be designed either as steel beam or composite beam when headed shear connectors connect concrete slab to top flange of steel beam. This paper presents a procedure to design cellular composite beams according to EN 1994-1-1. In addition, a parametric study is carried out to evaluate the influence of circular opening geometry to ultimate load and failure mode of a series of cellular composite beams. As a result, an optimal dimension of cellular beam is proposed. Article history: Received 28 February 2018, Revised 22 March 2018, Accepted 27 April 2018

Experimental investigation of low velocity impact on textile cellular composite with different energy construction

Cellular composite, with an array of regular hexagonal cells in the cross section, is a type of textile composites having the advantage of being light weight and energy absorbent over the solid composite materials. However, when it is under the same energy level of low velocity impact with different tup mass and velocity, its behavior is yet unknown. In the experiment, four groups of samples, with twelve geometrical variants have been systematically created for the impact testing. The impact test is running in two categories with one type of low velocity impact with initial velocity of 5.5 m/s by the tup mass of 0.55 kg, and another testing under the similar impact energy but with a lower initial velocity around 2.0 m/s with heavier tup mass of 4.52 kg. The impact energies in the above cases are very similar about 8.5 J, which indicates that the impact energy is the same while the energy construction is different. After the test, it is found that composite with medium cell size has more stable mechanical performances under various exposed impact conditions. It is also concluded that composites with big cell size are much easier to be destroyed under heavier impact tup, therefore, under condition of more critical loading force, it is necessary to find a way to enhance the big cell sized composites’ wall material in order to strengthen their structure performances. The results of this work provide a reference for the researchers who are kneeing to investigate the impact mechanism of textile cellular composites.

Experimental Research on the Triangular Lattice Type Polymer Based Composites Structures for Sandwich Panels Construction

The paper presents experimental results on the mechanical behaviour for a polymer based composite sandwich panel tensile and bending tested, which uses, one by one, a cellular composite core fabricated by additive manufacturing of four different types of polymeric materials: ABS (acrylonitrile butadiene styrene), PC (polycarbonate), PLA (polylactide) and CF (polylactide + 40% carbon fibre), with the thickness of 3 and 5 mm. This research focuses on comparative analysis of the core thickness increase effect on the structure�s strength. Experimental tests carried out on standardized test-pieces with specialized laboratory equipment, are highlighting similar mechanical behaviour and are showing also an increase of composite stiffness with the increase of core thickness, at the same time, the arrangement of the cellular lattice structure has a significant effect on the structural strength.

Research on Using AlMg10-SiC Cellular Alloys for Fluids Filtering

The paper presents some aspects of theoretical-experimental researches on the possibility of obtaining filters from a cellular metallic composite, based on theoretical considerations and practical aspects of the fluid environment, filter elements and the specific equipment that can accommodate this kind of filter. Thus, development of such new and performant filtering technologies, based on multifunctional materials, is currently conditioned by the design and development of cellular structures, with properties adapted to the filtering and functioning demands, structures that can reach operating temperatures between 150 and 2000oC. It was examined the possibility of obtaining alloys with cellular structure directly from casting process, alloys with high porosity, adjustable size and distribution of pores and high thermo-mechanical properties, which can be adapted for applications in the field of fluids filtration at temperatures above 100°C, fluids which can be chemically corrosive. The AlMg10-15% SiC cellular composite was obtained by means of melt bubbling method. We chose this type of material due to its achieved overall morphology: pores are uniform distributed throughout the mass of the material and they are connected through communication channels in the entire volume of the metallic composite. Through the conducted filtration tests we obtain the following values: filter fineness 97 μm, filtering capacity β97 = 8 and filtration efficiency E97 = 87.5 %. In accordance with determined filtering characteristics, the cellular metallic composite AlMg10-15% SiC belongs to the filters materials class that ensure a purity of the filtered fluid corresponding to a purity grade 6, in accordance with NAS 1638 and ISO 4406-1999.