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1

Influence of textile grid forms on tensile mechanical behaviors of carbon textile-reinforced composites with polyethylene (PE) short fibers

Wu Zhiyan, Deng Mingke, Tian Ting, Dong Zhifang, Sun Yanting, Zhang Wei

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 2

art. no. e103, 2023

EN

Textile-reinforced composite (TRC) is a new material composed of finely grained cement-based concrete and textile grids, which can be a substitute for fiber-reinforced polymer (FRP) in strengthening applications. The diversity of the textile grid results in a difference in bond behaviors at the textile-matrix interface, which influences the tensile properties of TRC. Several researchers have investigated the tensile behaviors of TRC, mainly concentrating on the matrix strength, the content of short synthetic fibers, and the number of textile grids; discussions on the textile grid geometry, especially the coupling effect between the textile grid form and matrix category, remained limited. Therefore, this paper focuses on the effects of three carbon textile grids on the tensile behavior of TRC through a uniaxial tensile test; the design parameters also include the textile reinforcement ratio and matrix category. Twenty-seven groups of tensile samples were manufactured to investigate the effect of each variable on the crack distribution, failure pattern, stress-strain curve and characteristic parameter. The test results showed that flattening the roving diameter and especially thinning the coating depth ameliorated the matrix-to-textile permeability, and consequently improved the tensile mechanical properties of TRC. The enhancement level of tensile strength by increasing the textile reinforcement ratio was lower than that by optimizing textile grid form. In terms of different textile grid forms, the effect of the matrix category on the tensile performance of TRC showed significant differences. Finally, an analytical model is presented to forecast the stress-strain behavior of TRC with textile rupture failure.

2

Effect of single roll drive cross rolling on the microstructure, crystallographic texture, and mechanical behavior of Al–Zn–Mg–Cu alloy

Kazemi-Navaee Amir, Jamaati Roohollah, Aval Hamed Jamshidi

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e41, 2022

EN

In this work, the effect of single roll drive cross rolling on the microstructure, crystallographic texture, hardness, tensile properties, and fracture behavior of AA7075 aluminum alloy was investigated. It was found that with increasing the thickness reduction, the grain size reduced and the average width of grain for the 40% deformed sample decreased to 3.7 ± 0.4 µm. Due to the nature of the cross-rolling process, several X-type shear bands were observed after 40% deformation. The recrystallization texture is notably intensified to its highest value of 4.4 × R, after only 20% cold deformation due to the occurrence of continuous dynamic recrystallization (CDRX). The intensity of recrystallization texture sharply dropped to its lowest value of 2.7 × R. This was due to the rotation of Goss-orientated new grains in the 20% deformed sample toward copper orientation during 40% rolling. With increasing the thickness reduction, the overall texture intensity significantly reduced owing to the nature of the cross-rolling process in which the rolling direction rotates 90° after each 10% strain. Two texture transitions were observed along τ fiber: rolling (copper) texture to recrystallization (Goss) texture after 20% thickness reduction and recrystallization to the rolling texture after 40% deformation. The hardness and strength increased by increasing the thickness reduction, while the ductility decreased. After a 40% thickness reduction, yield strength significantly increased from 138.3 ± 4.4 MPa (for initial sample) to the highest value of 580.5 ± 11.5 MPa, demonstrating 320% increment, in the 0° direction. This increment for 45° and 90° direction was 265% and 337%, respectively. By 40% rolling, the value of in-plane anisotropy (IPA) remarkably decreased to its lowest value of 3.4% due to texture weakening. With increasing the rolling reduction to 20%, the severity of Portevin–Le Chatelier (PLC) increased in the flow curves due to the occurrence of CDRX and also strengthening of the rotated cube {001} < 110 > and E {111} < 110 > components. With increasing the rolling reduction, the size of cleavage facets and the severity of delamination increased, and the number and depth of dimples decreased.

3

Study of the Properties and Cells Growth on Antibacterial Electrospun Polycaprolactone/Cefuroxime Scaffolds

Mijovic Budimir, Zdraveva Emilija, Bajsić Emi Govorčin, Slivac Igor, Dekaris Iva, Grgurić Tamara Holjevac, Ferri Tea Zubin

Autex Research Journal

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2020

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Vol. 20, no. 3

312--318

EN

Electrospun materials are good candidates for the design of tissue regeneration scaffolds as they can simulate the natural surroundings of tissue cells. The study proposes electrospun polycaprolactone (PCL)/cefuroxime (CFU) scaffolds for human cell culture and investigates the influence of the antibiotic content on scaffold morphology, thermal and mechanical properties. The increase in the CFU concentration resulted in the reduction of fiber diameter and number of deformations. It also influenced the reduction of scaffold thermal enthalpies and improved scaffold break strength. With regard to cell growth, the scaffolds showed precedence in greater colonization of the HeLa cells. Finally, these scaffolds showed compatibility with standard human cell lines, and thus they can be used for the repair of damaged tissues.

4

Finite Element Modeling for the Uni-Axial Tensile Behaviour of Metallic Warp-Knitted Fabric

Xu H.-Y., Jiang J.-H., Chen N.-L., Lin F.-B., Shao H.-Q.

Fibres & Textiles in Eastern Europe

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2018

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Vol. 26, no. 2 (128)

49-54

EN

The finite element analysis method (FEM), for its advantages of lower time and economic costing in predicting the mechanical properties of fabrics, was applied to warp-knitted fabrics. In this paper, two bar warp-knitted fabric knitted with wires was used as reflecting mesh antennas. Firstly the loop unit of the metallic warp-knitted fabric was simulated in 3-D by TexGen software. Secondly the 3-D loop unit model was inputted into ABAQUS software to form a model of the metallic warp-knitted fabric sheet for uni-axial tension analysis. Thirdly numerical results were obtained after setting the parameters in ABAQUS. Finally numerical results were verified by uni-axial tensile experiments on the metallic warp-knitted fabric. The results showed that the simulation was in good agreement with the experimental tensile process, where the transfer of yarns between loops when in low fabric elongation and in yarn elongation when in high fabric elongation were simulated by FEM of warp-knitted fabric in the tensile process. Also the same trend of tensile force was found in experiment and FEM results. Therefore it can be concluded that FEM can be used to predict the mechanical properties of warp-knitted fabric with a complex structure.

PL

Do przewidywaniu mechanicznych właściwości dzianin metalicznych zastosowano metodę elementów skończonych (FEM). Symulacji 3D dzianin dokonano przy użyciu dwóch rodzajów oprogramowania: TexGen i ABAQU. Wyniki symulacji zweryfikowano eksperymentalnie. Stwierdzono, że symulacja charakteryzowała się zgodnością z eksperymentalnie przeprowadzonym procesem rozciągania. Na podstawie wyników stwierdzono, że metoda elementów skończonych (FEM) może być z powodzeniem wykorzystywana do przewidywania mechanicznych właściwości dzianin o złożonej strukturze.

5

Experimental and Numerical Simulation of the Tensile Behaviour of a Biaxial Warp-knitted Composite

Gao X., Yang X., Li D., Li Y.

Fibres & Textiles in Eastern Europe

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2018

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Vol. 26, no. 6 (132)

71--76

EN

In this paper a composite reinforced with biaxial warp-knitted fabric and epoxy resin was manufactured by applying vacuum assisted resin transfer moldings (VARTM). The quasi-static tensile behaviour was experimentally tested in 0° and 90° directions, respectively. A finite element model of biaxial warp-knitted composites was developed on a meso-scale. The tensile behaviour of the composites was numerical simulated and compared with the experimental results. It showed that there is an approximate agreement between experimental and numerical results. There are maximum errors sum of squares of 14.52% and 33.29%. The finite element model of biaxial warp-knitted composites has higher accuracy, which can be used to study the static and dynamic mechanical properties.

PL

Wykonano kompozyt wzmocniony dwuosiową dzianiną osnowową i żywicą epoksydową z zastosowaniem próżniowego przenoszenia żywicy (VARTM). Quasi-statyczne właściwości rozciągania badano doświadczalnie odpowiednio w kierunkach 0° i 90°. Opracowano model skończonych elementów dwuosiowych kompozytów z dzianinami. Dokonano symulacji numerycznej zachowania kompozytów podczas rozciągania, a następnie porównano wyniki teoretyczne z wynikami eksperymentalnymi. Wykazano, że istnieje przybliżona zgodność między wynikami eksperymentalnymi i liczbowymi. Stwierdzono, że błędy maksymalne błędy kształtują się na poziomie 14,52% i 33,29%. Zaprezentowany model elementów skończonych ma wysoką dokładność i można go wykorzystać do badania statycznych i dynamicznych właściwości mechanicznych kompozytów.

6

The Effect Of Grain Size On The Mechanical Properties Of Aluminum

Jeong G., Park J., Nam S., Shin S.-E., Shin J., Bae D., Choi H.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2B

1287--1291

EN

Although many studies have focused on the unique plastic deformation behavior of nanocrystalline aluminum (e.g., the positive deviation from Hall-Petch relation, the unusual yield-drop phenomenon in tensile mode, etc.), the data reported by different research groups are inconsistent with each other, possibly because of different fabrication processes. In this study, aluminum samples with a wide grain-size spectrum – from a few micrometers down to 100 nanometers – are manufactured by powder metallurgy. The grain size was measured by X-ray diffraction analysis and transmission electron microscope observation. Furthermore, the tensile behavior, which varied according to a grain size, is discussed with a comparison of the theoretical models.