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1

Simulation and Heat Treatment Process of Carbon Nanotube Modified Aluminum Alloy (ZL105)

Zhang Zigi, Pan Zhilin, Li Rong, Zeng Qi, Liu Yong, Wu Quan

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 3

38--50

EN

To further improve the mechanical properties of carbon nanotubes (CNTs) modified aluminum alloy (ZL105), the first principle was used to build the atomic structure of the alloy system and the alloy system was simulated by the VASP. After that, the heat treatment process of the cast aluminium alloy material with CNTs to enhance the alloy performance by the orthogonal experiment. The results of the research show that: (1) The energy status of the alloy system could be changed by adding the C atoms, but it did not affect the formation and structural stability of the alloy system, and the strong bond compounds formed by C atoms with other elements inside the solid solution structure can significantly affect the material properties. (2) The time of solid solution has the greatest influence on the performance of material that was modified by CNTs. The solution temperature and aging temperature were lower strength affection, and the aging time is the lowest affection. This paper provides a new research method of combining the atomic simulation with the casting experiment, which can provide the theoretical calculations to reduce the experiment times for the casting materials’ performance improvement.

2

Flexural performance of hybrid fiber reinforced cement-based materials incorporating ceramic wastes

Wu Lipeng, Li Xuanhao, Deng Hai

Archives of Civil Engineering

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2023

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Vol. 69, nr 3

491--506

EN

Ceramic waste generated by demolition and manufacturing processes is a kind of widely discharged solid waste; its sustainable use can reduce resource extraction, energy consumption, and carbon emissions, thereby reducing the environmental impact. In this study, ceramic powder and ceramic sand were prepared using waste ceramic wall tiles. By using three water-to-binder ratios of 0.30, 0.32, and 0.34, five ceramic powder replacement rates of 10% to 50%, and completely using ceramic sand as the fine aggregate, specimens with large differences in mechanical properties were prepared. Firstly, the compressive strength was investigated. On this basis, hybrid fibers were employed to strengthen the new matrix material, and its bending resistance was experimentally studied. It was found that the incorporation of ceramic powder reduced the compressive strength of the matrix. The water-binder ratio significantly affects compressive strength at an early age. The effect of PVA fiber on improving the ductility of the new composite is distinct. Increasing the amount of steel fiber can effectively enhance the bending bearing capacity. With a ceramic powder dosage of 50%, the new composite has shown ductile failure characteristics, even with low total fiber content. The bending properties of this new composite material, which makes extensive use of ceramic waste, are well adjustable. The bearing capacity and ductility balance can be achieved with the steel fiber content of 1% and the PVA fiber content of 1.2% to 1.50%.

3

The Use of Waste Ceramic Optimal Concrete for a Cleaner and Sustainable Environment - a Case Study of Mechanical Properties

Najm Hadee Mahommed, Ahmad Shakeel

Civil and Environmental Engineering Reports

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2022

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Vol. 32, no. 3

85--115

EN

The present study aims to find out the optimal use of ceramic powder and ceramic aggregate (both fine and coarse) as a possible substitute for Ordinary Portland Cement (OPC 43 grade) and natural aggregate (fine and coarse), respectively, in concrete, where focused on investigating the mechanical properties of waste ceramic concrete. The performance of this modified concrete was evaluated in terms of Compressive Strength (CS), Tensile Strength (TS), Flexural Strength (FS), and Combined Flexural and Torsional strength (FTS) obtained based on various experimental tests conducted on a total of 192 samples (48 cubes, 48 cylinders, 96 beams). The test results showed that ceramic waste material as a partial replacement for natural aggregate, cement, and fine aggregate provides better performance in terms of CS, TS, and FTS at optimal percentages- 20% ceramic aggregate, 10% ceramic powder, and 10% ceramic fine aggregate (Fineness Modulus 2.2) respectively in M25 grade concrete. Using ceramic waste as a partial replacement to prepare concrete has a lot of benefits from the economic, environmental, and technological point of view. Moreover, it offers a possibility for improving concrete's durability, which is vital.

4

Benefits of using amorphous metallic fibers in concrete pavement for long-term performance

Yang J. M., Shin H. O., Yoo D. Y.

Archives of Civil and Mechanical Engineering

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2017

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Vol. 17, no. 4

750--760

EN

This study aims to examine the implications of amorphous metallic fibers on the mechanical and long-term properties of concrete pavement. Two different amounts of amorphous metallic fibers were incorporated into concrete, and plain concrete without fibers was also adopted as comparison. Test results indicated that the overall mechanical properties of concrete were improved by including the fibers, and the improvement increased when a higher amount of fibers was used. In particular, the equivalent flexural strength and flexural strength ratio were substantially improved by incorporating the amorphous metallic fibers. This may enable the thickness of airfield concrete pavement to decrease. The resistance to surface cracking of concrete pavement by repeated wheel loading was also improved with the addition of amorphous metallic fibers. In addition, by adding 5 kg/m3 and 10 kg/m3 amorphous metallic fibers in concrete pavement, roughly 1.2 times and 3.2 times longer service life was expected, respectively, as compared to their counterpart (plain concrete). Based on a life cycle cost analysis, the use of amorphous metallic fibers in concrete pavement was effective at decreasing the life cycle cost compared to plain concrete pavement, especially for severe traffic conditions.

5

Improvement of the mechanical performances of concrete cylinders confined actively or passively by means of SMA wires

Tran H., Balandraud X., Destrebecq J. F.

Archives of Civil and Mechanical Engineering

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2015

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Vol. 15, no. 1

292--299

EN

The present study deals with crush tests of concrete cylinders confined by shape memory alloy (SMA) wires. Two cases were considered. First, an active confinement was achieved by wrapping a wire previously prestrained in martensitic state and then subjected to the memory effect. Second, a passive confinement was obtained by using the same SMA, but in austenite state. For comparison purpose, an unconfined cylinder was also tested. The influence of the unwrapped zones of the confined cylinders was also investigated, leading to the use of a specially designed device to avoid premature failure in these zones. The comparison between active and passive confinements was investigated. The test results show that stiffness, strength and ductility are significantly improved in the case of the active confinement.

6

A new lightweight masonry block: Thermal and mechanical performance

Sousa L. C., Sousa H., Castro C. F., Antonio C. C., Sousa R.

Archives of Civil and Mechanical Engineering

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2014

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Vol. 14, no. 1

160--169

EN

The concerns with masonry building envelope performance, particularly thermal efficiency, are causing major changes in masonry solutions, mainly in south European countries, where traditionally the mild winter climate justified the use of high thermal masonry wall performance. The new European Directives regulations require different solutions. This paper describes the development a new masonry system, based on lightweight concrete units, intended for construction of large single leaf external walls without thermal insulation materials. A detailed analysis and optimization has been performed by FEM, under thermal point of view. This work was followed by a set of experimental tests in order to characterize the mechanical behavior of single units and masonry specimens. The concerns with productivity and ergonomics are also considered according their importance to the solution cost.

7

Influence of wet chemistry treatment on the mechanical performance of natural fibres

Koziol M., Bogdan-Wlodek A., Myalski J., Wieczorek J.

Polish Journal of Chemical Technology

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2011

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Vol. 13, nr 4

21-27

EN

The paper presents determination of the effect of various chemical treatment on the strength of 288 tex jute yarn arisen from the plain weave fabric produced by LENTEX, Poland. The yarn was put to alternative treatments in: NaOH and KOH water solutions with various concentration (from 1 to 15%) and treatment duration (from 0.5 to 6 hours), vinyl acetate, methanol and toluene diisocyanate. After the treatment it was put to tensile tests. Yarn diameter and elementary fibre twist angle were also measured using MICRO PROF FRT optical profilographometer. The SEM micro-photographs have also been performed in order to evaluate the structural changes of the yarn after the treatment. Optimal conditions of alcali-treatment are: 5% concentration and 2h duration for NaOH, 3% concentration and 4h duration for KOH. Such treatments give a growth in yarn rupture force up to 10% and they are well applicable in composite materials manufacturing. Also interaction with vinyl acetate and toluene diisocyanate has practically not negative influence on the mechanical performance of the yarn. Two effects were observed which can explain the influence of chemical treatment on mechanical performance of jute yarn: swelling and change in the orientation of elementary fibres.

8

Analysis of bionic films using finite element method

Wang J., Lan W.

International Journal of Applied Mechanics and Engineering

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2002

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Vol. 7, Spec. is

203-208

EN

Bionic coatings have wonderful mechanical properties, and are used in micro-electronic mechanical systems (MEMS) as a method to prolong their service lives. The authors studied the design process and performances of a kind of bionic coatings. The mechanical properties of different integrated coatings were analyzed with a finite element method. Two kinds of systems, i) with gradient coatings and ii) with integrated coatings, were studied. The results of stress distribution show that systems with the integrated coatings have more advantages over the gradient coating systems. And the effects of friction on subsurface stress field were also analyzed.