Papers by Keyword: Tensile Strength

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Authors: Anton Gnidenko
Abstract: Quantum-mechanical calculations were performed for investigation of tensile strength for WC/Co/WC systems with the thickness of the cobalt interlayer of 3 and 7 atomic layers. It has been shown that the cobalt interlayer increasing leads to decreasing of the tensile strength from 17 GPa to 14 GPa. In addition, vacancy-type defect formation reduces the tensile strength of about 2 times.
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Authors: Nadendla Srinivasababu, J. Suresh Kumar, K. Vijaya Kumar Reddy
Abstract: In the present work a new natural fibre i.e. sacred grass botanically called Imperata Cylindrica is introduced and it belongs to vedic grass family. The fibre is extracted by splitting method and is reinforced into the polyester matrix by hand lay-up technique for the fabrication of tensile, flexural, impact, dielectric test specimens as per ASTM procedures. Highest values of tensile strength (50.96 MPa), modulus (990.86 MPa) are observed for sacred grass fibre reinforced polyester composites at maximum volume fraction of chemically treated fibre. At 14.75 %, 35.89 % sacred grass fibre volume fraction the composites exhibited flexural strength, modulus of 43.19 MPa, 4.81 GPa respectively. Impact strength of 92.53 kJ/m2 is obtained for the composites reinforced with 34.73 % volume fraction of sacred grass fibres. The dielectric strength of the composites varies from 10 to 6.66 kV/mm for composites reinforced with fibres from minimum (6.26 %) to maximum (32.25 %) fibre content.
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Authors: Chen Li, Sheng Ling Xiao
Abstract: In this article, the changes of the polyvinyl chloride (PVC) film properties and its law are analyzed during the ultraviolet and thermal aging. Using accelerated aging methods in laboratory,it was found that the tensile strength by ultraviolet aging fell down, on the contrary, it raised by thermal aging. This result indicate that PVC film was not aged to reduce the tensile strength at 50°C for 120h.We found the air permeability curves rose firstly then to decline, and the moisture permeability of PVC film curves declined by the two aging methods. The effects of the ultraviolet aging on the air and moisture permeability were a marked decrease.
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Authors: Ping Li, Yong Chi Li, Shi Wei Duan, Rui Yuan Huang
Abstract: In order to obtain the tensile strength of the C40 concrete accurately, the comparative study between Brazilian disc splitting experiment and the direct tensile experiment is conducted with a self-modified tensile loading device. The study shows that the tensile strength observed from the direct tensile experiments (3.64MPa) is lower than that from the experiments (5.44MPa). A comprehensive analysis of experimental results is conducted focusing on the perspectives of the specimen failure forms, energy dissipation, the correlation of strength and hydrostatic pressure etc. The study suggests that the main reasons for the differences between Brazilian tensile experimental strength and direct tensile experimental strength include the surface energy required by the specimen destruction, the bond strength between the aggregate, the hydrostatic pressure in the process of loading and other factors.
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Authors: Li Dai, Xiong Jun He, Feng Shen
Abstract: It is necessary to research on the long term structural behavior of GFRP bars in concrete by limited samples. The two models, Arrhenius Equation and Fick’s Law were compared to form a long-term durability prediction thinking. Based on the work and ideas of the prior researchers, a detailed derivation of the iterative equation on the Bayesian prediction was conducted. Especially, a new likelihood function was set up to solve the long term behavior prediction of GFRP bars in concrete with less information. Then a new and effective solution method was developed. The residual strength behavior of GFRP bars in concrete beams after seven years’ environmental exposure was analyzed. The results showed that the theoretical predictions and experimental data were very close and theoretical prediction model was reasonable.
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Authors: Tian Guo Zhou, Peng Li, Xue Fei Zhang
Abstract: ɸ9mm aluminum alloy rods were prepared by Castex process with on-line solution. The rods were subsequently cold-drawn to ɸ 4 mm wires followed final artificial aging treatment. The microstructures and properties of ɸ 4 mm finish wires were investigated. The results show the tensile strength and equivalent conductivity of the T6-treated wires are 340MPa and 54.21%IACS respectively, it is good competent in the requirement for aluminum alloy-reinforced.
1046
Authors: Seyed Majid Safi, M.K. Besharati Givi
Abstract: In this paper, a modified up-quenching heat treatment method to the ASSAB 705M steel (ultra high strength steel) is proposed. A low alloy steel (0.33%C), was used to study the effect of isothermal austempering, successive austempering and modified up-quenching austempering heat treatment on the mechanical properties. The specimens, were cut from a bar with 25mm diameter and after achieving the best temperature and time of austenitizing, austenitized at for 60 min and followed by quenching at for the high austempering temperature to achieve the upper bainite morphology and at for the lower austempering temperature to achieve the lower bainite morphology. In the case of successive austempering, the specimens were first austempered at for different periods (500 sec and 60 sec) and then austempered at for 1000 sec to achieve the mixed structure of upper bainite and lower bainite morphology. The specimens selected for up-quenching, after austenitization were quenched to below ( ) for 120 sec. followed by heating at to achieve the mixed structure of tempered martensite and lower bainite and to achieve the mixed structure of tempered martensite and upper bainite for 1000 sec. All of the processes were performed in the salt bath furnaces. Experimental results are presented and the advantages of the modified method are discussed. As well, it is shown that the best combination of strength and ductility can be achieved by the proposed heat treatment method. This modified method, can offer techniques that simultaneously improve not only strength 12 %( compare with results of strength after other heat treatment methods), but also ductility 38 %( compare with results of ductility after other heat treatment methods). While, conventional heat treatment of ultra high strength steels (UHSS) cannot always meet the strict engineering requirements for improved strength and ductility simultaneously. It has been shown that the mixed structure of tempered martensite and lower bainite that has been suggested in this investigation offers a good combination of strength and ductility. The technical reason for this superiority returns back to the fact that it has increased dislocation density. As a result of the increment of the dislocation density, in the morphology, the inter lath carbide (e.g. cementite) decreases, and the intra lath carbide increases. This modified austempering is applicable to all the ultra high strength steels, has noticeable economic advantages because it is simple. Use of this modified austempering for heavy parts, leads to the lightness of heavy parts and combination of the thermomechanical methods with this modified austempering can yield even much more improvements.
1109
Authors: M.H. Norhidayah, Arep Ariff Hambali, Mohd Yuhazri bin Yaakob, M. Zolkarnain, Taufik, H.Y. Saifuddin
Abstract: Nowadays, natural fiber is an interesting option and it is the most widely applied fiber in composite technology. The natural fibers are used in most of the industries and are increasingly being considered as reinforcements for polymer-matrix composites because they are perceived to have sustainability value. This research paper aims to enlighten the existing development in natural fiber composites in automotive applications. Additionally, this research paper reviews the related papers from the year 2006 until 2013. Finally, a summary of selected products that have been identified by car manufacturers were identified.
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Authors: Qiao Zhu, Lin Hua Jiang, Jin Xia Xu
Abstract: In this article, some empirical and theoretical models accounting the relationship between the strength and pore structure of cement-based materials is reviewed and analyzed. From the literature review and analysis, it can be found that the total porosity can be singly used to characterize the relationship between compressive strength and pore structure, but can not be applied into describe the relationship between pore structure and tensile strength. Another major parameter of pore structure - pore size distribution, will have a major impact on strength; the relationship between pore structure and tensile strength is for most models of cement paste, without the consideration of aggregate, and the application of the model must comply with the relevant assumptions. The research on the relationship between the tensile strength of concrete is still at a preliminary stage, requiring more theoretical and experimental study.
862
Authors: Maurizio Ferrante
Abstract: It is well known that the low ductility of nanostructured materials seriously impairs their commercial development. In its turn that mechanical property is associated to the work-hardening behaviour and the vast literature on this relationship is a measure of its importance. This paper presents a short review of the basic models of work-hardening, dealing initially with conventional “coarse” grain metals and alloys, then moving to the behaviour of sub-microcrystalline materials within the bounds of Al alloys and Equal Channel Angular Pressing. Finally, the interrelations of tensile properties, work-hardening behaviour and microstructure are illustrated by data obtained on a precipitation and a non-precipitation hardening Al alloys, namely Al-4%Cu and AA3004. Results show that low temperature aging results in higher strength and high work hardening rate, besides high ductility. The effects of precipitation and of annealing heat treatments are discussed.
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