E. Donnelly; F. M. Weafer; T. Connolley; P.E. McHugh; M. S. Bruzzi
Abstract
For many years, computational modelling and simulation studies have been used by developers to advance device design and have been reported in regulatory medical device submissions. However, cardiovascular stent materials in such computational models are typically assumed to behave as a continuum. This ...
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For many years, computational modelling and simulation studies have been used by developers to advance device design and have been reported in regulatory medical device submissions. However, cardiovascular stent materials in such computational models are typically assumed to behave as a continuum. This approach assumes that bulk material properties apply to the micro-sized structure, i.e. material behavior is scale independent. However, as size is reduced, mechanical size effects arise as the grain size to specimen width ratio drops below a critical value. These size effects cause material behavior to deviate significantly from bulk material behavior. If such a deviation in material behavior is to be captured within computational models, it is necessary to represent the crystalline structure of a metal and to capture the anisotropic behavior of individual grains within these models. This paper describes the development of such a modelling methodology to investigate the phenomenon of strain localization within grains of a 316L stainless steel specimen under fatigue loading conditions.
Demudu B. Dommisa; Raj K. Dash*
Abstract
In this work the effect of the precursor graphite on the structure and morphology of the graphene oxide and reduced graphene oxide are investigated by considering three different sizes source graphite such as 2-15, <45 and 170-840μm respectively. All the three graphite were oxidized by Modified ...
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In this work the effect of the precursor graphite on the structure and morphology of the graphene oxide and reduced graphene oxide are investigated by considering three different sizes source graphite such as 2-15, <45 and 170-840μm respectively. All the three graphite were oxidized by Modified Hummer’s method and further reduced by hydrazine hydrate by maintaining same synthesis conditions. The results demonstrated that the oxidation process is size dependent of the source graphite.The results revealed that smaller size graphite is fully oxidised as compared to larger sizes and also functionalized more. Few layers (less than 4-5) crystalline, less disorder and unfolded reduced graphene oxides are obtained when smallest size graphite is used as the source material. The water molecules present in the graphene oxide synthesised from larger size graphite as source material are higher and that can lead to the the occurrence of polycrystalline in structure, more disorder and wrinkled or folding reduced graphene oxide. Therefore, this study can open a new pathway to synthesis more crystallinity, less disorder and wrinkled free or unfold reduced graphene oxide for several potential applications.
D. Srinivas Rao; Raj Kishora Dash
Abstract
The effect average alumina nanoparticle sizes on the long term dispersion stability of biodiesel based nanofluids was investigated. Alumina nanoparticles having two different average sizes (~13nm and ~28nm) were dispersed in the Jatropha biodiesel as the base fluids. The effect of alumina (Al2O3) nanoparticles ...
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The effect average alumina nanoparticle sizes on the long term dispersion stability of biodiesel based nanofluids was investigated. Alumina nanoparticles having two different average sizes (~13nm and ~28nm) were dispersed in the Jatropha biodiesel as the base fluids. The effect of alumina (Al2O3) nanoparticles sizes on the stability of nanofluids was investigated to achieve more stable nanoparticles dispersed nanofluids having longer duration for potential use in alternative fuel energy applications. Different volume fractions (VF) such as 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% nanofluids were prepared by using two different sizes of alumina nanoparticles (~13nm and ~28nm) by using the surfactants Span 80 and Tween 80 in the ratio of 1:1. The results revealed that the nanofluids having the smaller average sizes alumina nanoparticles and 0.1% volume fraction were stable for more than one year as compared to the larger (two times) size nanoparticles having same 0.1% volume fraction. Such long term stable biodiesel based nanofluids can be used as the alternative fuel energy for future automobiles and transportation sectors due to the fuel properties of such nanoparticles dispersed nanofluids retaining the commercial diesel properties.