High-strength flowable mortar reinforced by steel fiber
An experimental study was conducted on High-Strength Flowable Mortar (HSFM) reinforced at different percentages of steel fiber (0, 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75 and 2.0% as volumetric fractions) to determine the density, compressive strength, static modulus of elasticity and flexural strength. The load-deflection curves under a static flexural load were established, and the flexural toughness indices were obtained in accordance with ASTM C1018. The results indicate that by increasing the fiber content up to 1.75%, the flexural strength and toughness indices are increased. The density, compressive strength and static modulus of elasticity also increased using steel fiber.
Jaroslav Majko, Marián Handrik, Milan Vaško and Milan Sága
Continuous fiber fabrication technology, developed by Markforged and used in MarkTwo printers, allows using of reinforcing fibers, which improve mechanical properties of produced parts. The technology enables choosing of two fiber deposition strategies: isotropic fiber fill and concentric fiber fill. With the isotropic fiber fill, there is an option to set up various fiber angles in each layer. The article is focused on stress distribution analysis using FEM in a matrix and individual reinforcing fibers of specimens loaded to uniaxial tension. Main observed parameters are stresses in matrix and fiber and usage of the reinforcing material.
The use of new reinforcing materials and products in the construction industry requires their thorough assessment for a variety of design situations. One of the significant effects is the shrinkage of the concrete, which in the case of asymmetrically reinforced elements can cause the element to be deformed. The research was focused on slabs asymmetrically reinforced by composite reinforcement (GFRP) and by three reinforcement stages. To eliminate the effect of concrete non-homogeneity, a concrete slab of the same dimensions was made of the same concrete. The results show a significant effect of shrinkage on reinforced slabs.
Textile reinforced concrete (TRC) is an eco-friendly material with a high freedom in design. As soon as complexcurved parts are to be designed, the question of the drapability of the reinforcing materials arises. Differentprocess parameters can be modified in the production of the reinforcing textiles which strongly influence thehandling and the draping behaviour. To be able to choose a textile structure in the design stage which fulfils therequirements concerning drapability, a new test method was developed. This article describes this test methodand shows results of a test series on different textile structures, including a brief discussion of the results. Finally,a transfer to a sample geometry is shown.
Richárd Horváth, Róbert Gábor Stadler and Kristóf Andrásfalvy
The use of fiber-reinforced plastics has increased significantly in the past decades. Consequently, the demand for finishing and machining of such materials has also escalated. During machining, the fiber-reinforced materials exhibit machining problems dissimilar to the problems of metals. These are fiber pull-out, fiber breakage in the cutting zone, matrix smearing and delamination. The purpose of this experiment is to investigate the characteristics of the resultant force (Fe) dur-ing the milling of carbon fiber reinforced plastic as a function of input machining parameters. For the force measurements, CFR with perpendicular (0°-90°) fiber orientation was machined. The experimental design involved the central composite design method. To analyze and evaluate the measurements, we applied the response surface methodology.
Milon Hossain, A.H.M Fazle Elahi, Shahida Afrin, Iqbal Mahmud, Haeng Muk Cho and Mubarak Ahmad Khan
An experiment was carried out using glass fiber (GF) as reinforcing materials with unsaturated polyester matrix to fabricate composite by hand layup technique. Four layers of GF were impregnated by polyester resin and pressed under a load of 5 kg for 20 hours. The prepared composite samples were treated by prolonged exposure to heat for 1 hour at 60-150°C and compared with untreated GF-polyester composite. Different mechanical test of the fabricated composite were investigated. The experiment depicted significant improvement in the mechanical properties of the fabricated composite resulted from the heat treatment. The maximum tensile strength of 200.6 MPa is found for 90°C heat-treated sample. The mechanical properties of the composite do seem to be very affected negatively above 100°C. Water uptake of the composite was carried out and thermal stability of the composite was investigated by thermogravimetric analysis, and it was found that the composite is stable up to 600°C. Fourier transform infrared spectroscopy shows the characteristic bond in the composite. Finally, the excellent elevated heat resistant capacity of glass-fiber-reinforced polymeric composite shows the suitability of its application to heat exposure areas such as kitchen furniture materials, marine, and electric board.
Sandra Veličković, Slavica Miladinović, Blaža Stojanović, Ružica R. Nikolić, Branislav Hadzima and Dušan Arsić
Hybrid materials with the metal matrix are important engineering materials due to their outstanding mechanical and tribological properties. Here are presented selected tribological properties of the hybrid composites with the matrix made of aluminum alloy and reinforced by the silicon carbide and graphite particles. The tribological characteristics of such materials are superior to characteristics of the matrix – the aluminum alloy, as well as to characteristics of the classical metal-matrix composites with a single reinforcing material. Those characteristics depend on the volume fractions of the reinforcing components, sizes of the reinforcing particles, as well as on the fabrication process of the hybrid composites. The considered tribological characteristics are the friction coefficient and the wear rate as functions of the load levels and the volume fractions of the graphite and the SiC particles. The wear rate increases with increase of the load and the Gr particles content and with reduction of the SiC particles content. The friction coefficient increases with the load, as well as with the SiC particles content increase.
The purpose of this research is unsatisfactory state of knowledge of the abrasive wear of composites with thermoplastic polymer as matrix material and reinforcing material in the form of short and focused carbon fibers that can be used in additive manufacturing technologies. The paper presents a conceptual design of an extrusion head used in Fused Deposition Technology, which allows for the implementation of appropriately stacked fibers at the level of detail production. Finite element simulation was performed to simulate the thermal effect of the system to demonstrate the effect of head cooling on the system. The assumed extrusion temperature of the material was obtained at a uniform nozzle temperature and stable temperature of the entire system. Flow simulation of thermoplastic polymer was carried out in the designed extrusion nozzle. By supplying 0.5 mm wire of 1.75 mm diameter thermoplastic material to the nozzle, the extrusion rate was 0.192 m/s. The proper design of the extrusion head for the intended applications has been demonstrated and the purpose of further research in this field has been confirmed.
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