Papers by Keyword: Strain Rate Sensitivity (SRS)

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Authors: S. Vijay Ananth, M Kumerasan, K Kalaichelvan
Abstract: Superplastic forming in Al6063/SiCp composites having a wide range of applications in aerospace and automobile industries due to the high strength and wear resistance[7]. High percentage of elongation was obtained only at high temperatures. At high temperatures liquid phase will form in the grain boundaries. Due to the liquid phase, grain boundary sliding was easy to get the Newtonian viscous flow[1]. In composites high ductility was obtained only the temperature more than 560°C. The maximum dome height of 19 mm was obtained at 580°C. Temperature is more than 600°C the material was failed, fracture was occurred.
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Authors: Ying Chen Zhang, J.N. Huang, Hong Yan Wu, Y.P. Qiu
Abstract: The role of both nano-sized of plasma treated Nano Titanium Dioxide particles and strain rate on the tensile properties of plasma treated Nano Titanium Dioxide particles/PP/PLA nano-composites filaments (PTNTOPPCF) was studied. Filaments tensile samples of PTNTOPPCF were prepared by a twin screw mixer- twin screw extruder with a particle content of 0.3~1%. The influence of surface treatment of the particles, with and without low-temperature oxygen plasma treatment, on the physico-mechanical properties was studied. The tensile tests were carried out, differential scanning calorimetry (DSC) and SEM were used in this investigation. Tensile tests were done at different strain rates. The addition of plasma treated Nano Titanium Dioxide particles to PP/PLA caused a change in Young's modulus and yield stress of its composites. The experimental results also showed that the strain-rate sensitivity of PTNTOPPCF changed as plasma with and without oxygen treated Nano Titanium Dioxide particles was added to it with different o.w.f.. We found that the models lead to estimates of activation volumes in the range 4−40nm3 for truly nanocrystalline material. Activation volumes were found to changing un-monotonically with oxygen plasma treatment. The findings were found to be in accord with available experimental evidence in both a quantitative and qualitative manner. Deficiencies in the available experimental evidence were noted, specifically in the context of explaining some of the difficulties in comparing theoretical predictions to experimental observation.
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Authors: Hong Yan Wu, Wei Zhang, Ying Chen Zhang, Yi Ping Qiu
Abstract: The strain rate sensitivity of Oxygen plasma treated carbon nanotube sol-gel coating Basalt and concurrent microstructural evolution investigated. Both the materials are strain rate sensitive and the change in index parameter of strain rate sensitivity with strain reflects the change in micromechanisms of deformation and mode of fracture. From the SEM micrographs, an increase in surface roughness can observed and the degree of fibrillation decreased after helium and oxygen plasma treatment. Contact angle analysis showed the treated Basalt filament had lower contact angles than the untreated one. Based on FTIR results, the change of wettability and surface energy is attributable to polar groups on the fiber surface introduced by the treatments. Deformation processes in the Oxygen plasma treated carbon nano tube sol-gel coating Basalt involved craze-tearing and brittle mode of fracture, while plasma treated carbon nano tube in nano-composites filaments predominantly characterized by wedge, ridge tearing, fibrillation and brittle fracture. Depend yield stress of the Oxygen plasma treated carbon nanotube sol-gel coating Basalt with strain rate follows Eyring’s equation.
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Authors: Tomokazu Masuda, Toshiro Kobayashi, Lei Wang, Hiroyuki Toda
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Authors: Zhi Guo Fan, Chao Ying Xie
Abstract: Ultrafine-grained (UFG) CP Ti were successfully prepared by Equal Channel Angular Extrusion (ECAE) at 390°C~400°C, small than 0.5 um in size. The compressive tests for coarse grain (CG) and UFG Ti were carried out at room temperature (RT) and 77K. UFG Ti showed excellent ductility and higher strength than CG Ti at RT and 77 K. The strain hardening of UFG Ti was improved at 77 K. The compressive ultimate strengths of CG Ti and UFG Ti were both enhanced as the strain rate increased, but CG Ti showed more obvious temperature and strain rate dependence of flow stress, comparing with UFG Ti. When the strain rate increased to 1×10-1/s, the compressive ultimate strength of UFG Ti was kept almost constant, while the ultimate strength of CG Ti increased to the strength level of UFG Ti.
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Authors: V.S.R. Murthy, Samar Das, G.Banu Prakash, G.S. Murty
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Authors: Zoltán Száraz, Zuzanka Trojanová
Abstract: The deformation characteristics of the WE54 magnesium alloy reinforced by 13% of SiC particles have been investigated in tension at elevated temperatures. Composite material was prepared by powder metallurgy technique. The strain rate sensitivity parameter m has been estimated by the abrupt strain rate changes (SRC) method. SRC tests and tensile tests with constant strain rate ( ) were performed at temperatures from 350 to 500 °C. Increased ductility has been found at high strain rates. The corresponding m value was 0.3. The activation energy Q has been estimated. Microstructure evolution has been observed by the light microscope and scanning electron microscope.
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Authors: Shan Qing Xu, Dong Ruan, John H. Beynon, Guo Xing Lu
Abstract: The compressive behavior of two closed cell aluminum foams (Alporas and Cymat) were investigated under various strain rates from 10-3 to 102 s-1 using compressive tests conducted on MTS and Instron test machines. High speed camera videos show that localized deformation occurs in Alporas foam specimens uniformly, but not in Cymat foams. The stress-strain curves for Alporas foams are smooth and regular, while they oscillate dramatically for Cymat foams. Alporas foams exhibit strain rate sensitivity, i.e. with an increase in strain rate, the normalized plateau stress and energy absorption capacity increase. The plateau stress for Cymat foams was more sensitive than Alporas to strain rate, but the energy absorption less so, at least at a nominal relative density of 10%.
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Authors: Benjamin Erzar, Pascal Forquin
Abstract: Concrete is a material used all over the world for civil engineering but the mechanisms governing its dynamic behaviour are still not well understood. In this work, spalling tests and edge-on impact experiments have been used to determine the influence of the free-water contained in pores and micro-cracks on the dynamic strength and on the fragmentation process. Moreover, spalling tests have been also used to identify the main mechanisms leading to the difference of behaviour observed between wet and dry concrete.
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