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- Athanasopoulos, Stefanos D., et al.
(författare)
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Mapping Grain Strains in Sand Under Load Using Neutron Diffraction Scanning
- 2018
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Ingår i: Micro to MACRO Mathematical Modelling in Soil Mechanics. - Cham : Springer International Publishing. - 2297-0215 .- 2297-024X. - 9783319994734 - 9783319994741 ; , s. 23-33
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Bokkapitel (refereegranskat)abstract
- Towards the improvement of the understanding of force/stress distribution in granular media under load, a new experimental approach is suggested. Neutron diffraction, a non-conventional experimental technique, has been successfully used to map the evolution of intragranular strains in sand specimens loaded in a novel plane-strain apparatus. Representative preliminary results from recent experiments are presented, focusing on the correlation between the macro- and micro-scale response of the material, to highlight the potential of the experimental approach.
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| 6. |
- Harati, Ebrahim, 1986-, et al.
(författare)
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Neutron Diffraction Evaluation of Near Surface Residual Stresses at Welds in 1300 MPa Yield Strength Steel
- 2017
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Ingår i: Materials. - : MDPI. - 1996-1944. ; 10:6, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- Evaluation of residual stress in the weld toe region is of critical importance. In this paper, the residual stress distribution both near the surface and in depth around the weld toe was investigated using neutron diffraction, complemented with X-ray diffraction. Measurements were done on a 1300 MPa yield strength steel welded using a Low Transformation Temperature (LTT) consumable. Near surface residual stresses, as close as 39 µm below the surface, were measured using neutron diffraction and evaluated by applying a near surface data correction technique. Very steep surface stress gradients within 0.5 mm of the surface were found both at the weld toe and 2 mm into the heat affected zone (HAZ). Neutron results showed that the LTT consumable was capable of inducing near surface compressive residual stresses in all directions at the weld toe. It is concluded that there are very steep stress gradients both transverse to the weld toe line and in the depth direction, at the weld toe in LTT welds. Residual stress in the base material a few millimeters from the weld toe can be very different from the stress at the weld toe. Care must, therefore, be exercised when relating the residual stress to fatigue strength in LTT welds.
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| 7. |
- Lyphout, Christophe, 1981, et al.
(författare)
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Residual Stresses Distribution Through Thick HVOF Sprayed Inconel 718 Coatings
- 2008
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Ingår i: Proceedings of the International Thermal Spray Conference (ITSC), Maastricht, Netherlands. ; , s. 588-593
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Konferensbidrag (refereegranskat)abstract
- Residual stress build up in thick thermal spray coatings is a property of concern. Coating adhesion to the substrateis influenced by residual stresses that are generated during the coating deposition process. In the HVOF sprayprocess, significant peening stresses are generated during impact of semi molten particles on the substrate. Thecombination of these peening stresses together with quenching and thermal mismatch stresses can be ofsignificant importance. Both numerical Finite Element Method (FEM), to calculate peening, quenching stresses, andexperimental methods, i.e. Modified Layer Removal Method (MLRM) and Neutron Diffraction, have been utilised in this work. The investigation was performed on thick Inconel 718 coatings on Inconel 718 substrates. Combined, these numerical and experimental techniques yield a deeper understanding of residual stress formation in the HVOF process and thus a tool for process optimisation. The relationship between the stress state and deposit/substrate thickness ratio is given particular interest.
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| 8. |
- Venter, Andrew M., et al.
(författare)
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Systematic investigation of residual strains associated with WC-Co coatings thermal sprayed onto metal substrates
- 2012
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972. ; 206:19-20, s. 4011-4020
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Tidskriftsartikel (refereegranskat)abstract
- Using penetrating high-energy synchrotron X-ray radiation and thermal neutrons, the residual strains and stresses associated with the high-velocity oxygen-fuel (HVOF) thermal spray coating of WC-Co on two different substrate materials with significantly different coefficients of thermal expansion (CTE) to that of the coating material, have been investigated in a systematic approach. This approach enabled quantification of the residual strain and stress contributions that emanate from the different processing steps associated with the coating process. An eigenstrain approach enabled direct comparison of the contributions of the different processing steps to the plastic strains. It is shown that the dominant contribution originates from the grit-blast surface preparation step. Contributions purely from the coating process are not distinguishable from that of the grit blasting process within the measurement accuracy. For the as-coated samples no obvious contributions ascribable to the differences in the CTEs of the substrates, or impact related effects are observed. (c) 2012 Elsevier B.V. All rights reserved.
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