Papers by Keyword: Toughness

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Authors: Chen Chen, Xiao Dong Jia, Hang Zhang, Ran Wei, Fu Shan Li
Abstract: In this paper, a centimeter-size Zr-Cu-Al-Nb bulk metallic glass (BMG) with high notch toughness of 107±13 MPa∙m0.5 was designed and fabricated by copper mold casting. With 1% Nb substitution for Zr in Zr48Cu45Al7 glass forming alloy, the glass forming ability (GFA) and toughness of the BMG were enhanced significantly. The coexistence of nano-crystallization and phase separation in the glassy matrix was observed in Zr47Cu45Al7Nb1, which would possibly lead to the high toughness of this alloy due to the easy and populous nucleation of shear bands and the increasing resistance of shear band propagation. The influences of nano-crystallization and phase separation on the toughness of BMGs are discussed in detail. The strategy utilized in this study provides a novel approach in search for new BMGs with high toughness and good GFA.
Authors: J.-Ph. Verhelle, P. Descamps, Marc Poorteman, Fabrice Petit, F. Cambier, Richard Duclos
Authors: Ta Yuan Han, Wei Ting Lin, An Cheng, Chin Cheng Huang
Abstract: This study is aimed to evaluate the tensile strength of cement-based composites which comprise polyolefin fibers and silica fume in the mixes. Material variables include water-cementitious ratio, dosage of silica fume, steel fiber length and dosage. Test results indicate that the compressive strength and direct tensile strength of specimens for fiber length of 25 mm are higher than that of 50 mm. The strength properties increase with increasing fiber content. Incorporation of fiber and silica fume in composites achieves significantly higher increase in compressive strength and direct tensile strength than only use of fiber or silica fume. In addition, the compressive strength, splitting tensile strength, direct tensile strength and impact resistance are fairly correlated. It contributes that the fiber content influences crack arresting ability and the silica fume influences interfacial bonding effectively.
Authors: C.K. Seal, M.A. Hodgson, W. George Ferguson
Abstract: During the mid 1990s earthquakes in Northridge, California, and Kobe, Japan, illustrated a lack of understanding of the behaviour of structural steels exposed to seismic loads. Under this type of load regime, structural steel members are subjected to fully plastic load cycles and unexpectedly brittle failures resulted. This paper presents a simple, yet powerful, method for predicting the accumulation of damage in a steel element, based on its toughness. In addition the damage parameter chosen provides an accurate prediction of when failure of the element can be expected to occur. The damage accumulation model developed allows for the deconvolution of complex load histories, such as could be expected to occur during a seismic event, in a systematic, stepwise manner. This approach is ideally suited to automation and could readily be implemented into a finite element model.
Authors: J.R. Moon
Abstract: It is now fairly well established that to achieve low values of the Paris exponent for the growth of fatigue cracks in PM steels, high values of fracture toughness are required. Fracture toughness is related to other measures of toughness, such as impact tests and the mechanical work that the material can absorb before fracturing. All of these are functions of the basic ductility of the material. A coherent picture of all these inter-relationships is presented.
Authors: Cun Bing Huang, Tie Cheng Lu, Li Bin Lin, Mu Yun Lei, Cun Xin Huang
Abstract: Transparent Mg-Al spinel ceramics of four different nonstoichiometries were obtained utilizing two-stage sintering technique of vacuum sintering and post hot isostatic pressing using MgO·nAl2O3 powders with n of 1, 1.3, 1.5 and 1.8, respectively, as raw materials. The mechanical properties of the ceramics were measured and indentation shapes and radial crack propagations were observed. The results showed that change of molar ratio of Al2O3 to MgO leads to variation of indentation shapes and crack propagations of the ceramics, resulting in the change of mechanical properties of the ceramics. The flexural strengths of the ceramics increase first then decrease with increasing n. However, the hardness and fracture toughness of the ceramics increase with increasing n. As a result, an optimal n for high performance ceramic is suggested to be 1.5. In addition, mechanisms of toughening and strengthening of the transparent ceramics have also been discussed.
Authors: Hee Seung Kim, Mi Young Seo, Ik Jin Kim
Abstract: Advanced engineering ceramic technology has very remarkable reputation in the high-tech fields such as semiconductor device manufacturing. ZTA (Zirconia Toughened Alumina), ruby and alumina is applied in the manufacturing of the capillaries that demonstrate high strength, fracture toughness and long life. The advantages of the new composite material over the standard ultra-fine grain high-density material have been proven in many applications especially for packages requiring less than 50μm capillary tip diameter. In this work, micro-structural evolution of ceramic composites and its correlation with important criteria in the selection of the suitable capillary material either ZTA composites or high-density ruby ceramics for a specific package applications will be discussed.
Authors: R.K. Bird, D.L. Dicus, I.N. Fridlyander, V.S. Sandler
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