Browsing by Author "Kristein, O"

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    Stress distribution in iron powder during die compaction
    (Australian Nuclear Science and Technology Organisation, 2013-09-10) Kisi, EH; Wensrich, CM; Luzin, V; Kristein, O
    Granular materials are extremely important in food production, minerals extraction, pharmaceuticals and powder metallurgy. They can be poured like a liquid and yet can support static shear stresses like a solid (mounds do not collapse), Granular materials are always locally and macroscopically inhomogeneous making algebraic constitutive models difficult to develop. Numerical analysis using continuum (finite element) or individual particle (discrete element) models are being widely explored [1,2]. However, there were previously no methods for their experimental validation. This paper reports the application of the neutron diffraction strain scanning method, originally developed for residual stress measurements within engineering components, to the problem of the stress distribution in granular Fe under a consolidating pressures Strains were measured in axial, radial, circumferential and an oblique direction using the neutron strain scanning diffractometer KOWARI at ANSTO(Sydney) and the full stress tensor as a function of position wvas able to be extracted (e.g. Fig l). Results will be presented for a both a straight Walled and a converging die. Typical results using the converging die are shown in Fig. l.
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    Verification of residual stresses in flash-butt-weld rails using neutron diffraction
    (The Bragg Institute, Australian Nuclear Science and Technology Organisation, 2005-11-27) Tawfik, D; Kristein, O; Mutton, PJ; Chiu, WK
    Residual stresses developed during flash-butt welding may play a crucial role in prolonging the fatigue life of the welded tracks under service loading conditions. The finished welds typically exhibit high levels of tensile residual stresses in the web region of the weld. Moreover, the surface condition of the web may contain shear drag or other defects resulting from the shearing process which may lead to the initiation and propagation of fatigue cracks in a horizontal split web failure mode under high axle loads. However, a comprehensive understanding into the residual stress behaviour throughout the complex weld geometry remains unclear and is considered necessary to establish the correct localised post-weld heat treatment modifications intended to lower tensile residual stresses. This investigation used the neutron diffraction technique to analyse residual stresses in an AS60 flash-butt-welded rail cooled under normal operating conditions. The findings will ultimately contribute to developing modifications to the flash-butt-welding procedure to lower tensile residual stresses which may then improve rail performance under high axle load conditions. © The Authors