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| 2. |
- Frachon, A., et al.
(författare)
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Sensitivity of numerical simulation to input data
- 2000
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Ingår i: Proceedings of PM2000 Powder metallurgy world congress and exhibition. - Tokyo : Japan Society of Powder and Powder Metallurgy. - 9784990021481
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Konferensbidrag (refereegranskat)
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| 3. |
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| 4. |
- Högberg, Ida, et al.
(författare)
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Brightness development of a hydrogen peroxide bleached spruce TMP. Comparisons of pre-treatments with DTPA and a separable chelating surfactant
- 2012
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 27:1, s. 50-55
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Tidskriftsartikel (refereegranskat)abstract
- In this investigation a new type of recoverable complexing agent (chelating surfactant) has been compared with a conventional complexing agent; diethylenetriamine pentaacetic acid (DTPA), in the metal ion sequestering of thermomechanical pulps (TMP) to be hydrogen peroxide bleached. After different degrees of washing of the pulps, bleaching experiments at different total alkali charges were performed with and without sodium silicate additions, and the ISO brightness of hand-made sheets was measured. The residual hydrogen peroxide in the bleaching liquor was also determined. No significant difference in either the brightness development or the residual hydrogen peroxide content could be detected between the pulps treated with equivalent molar ratios of the different complexing agents. Furthermore, the recovery of the chelating surfactant-manganese complexes from laboratory made white water by froth flotation was also studied. Two different foaming agents; sodium dodecyl sulphonate (SDS) and dimethyldodecylamine oxide (DDAO), were tested in the froth generation. After an addition of 160 ppm of DDAO, more than 80% of the manganese chelates could be recovered in the foam, containing 3% of the initial water mass.
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| 5. |
- Högberg, Ida, et al.
(författare)
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Use of chelating surfactants as complexing agents for removal of manganese from mechanical pulp fibres prior to hydrogen peroxide bleaching.
- 2011
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Ingår i: 16th International Symposium on Wood, Fiber and Pulping Chemistry - Proceedings, ISWFPC. - Tianjin : China Light Industry Press. ; , s. 682-686
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Konferensbidrag (refereegranskat)abstract
- In this investigation a new type of recoverable complexing agent (chelating surfactant) has been compared with a conventional complexing agent (DTPA) in the metal ion management of thermomechanical pulps (TMP) to be hydrogen peroxide bleached. After different degrees of washing of the pulps, bleaching experiments at different total alkali charges were performed with and without sodium silicate additions, and the ISO brightness of hand-made sheets was measured. The residual hydrogen peroxide in the bleaching liquor was also determined. No significant difference in either the brightness development or the residual hydrogen peroxide content could be detected between the pulps treated with equivalent molar ratios of the different complexing agents. Furthermore, the recovery of the surfactant-manganese complexes from laboratory made white water by foam flotation was also studied. Two different foaming agents, SDS and DDAO, were tested. After an addition of 160 ppm of the latter surfactant, about 80% of the manganese chelates could be recovered in the foam, containing 3% of the initial water mass.
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| 6. |
- Kajberg, Jörgen, et al.
(författare)
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Viscoplastic parameter estimation by high strain-rate experiments and inverse modelling : speckle measurements and high-speed photography
- 2007
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Ingår i: International Journal of Solids and Structures. - : Elsevier BV. - 0020-7683 .- 1879-2146. ; 44:1, s. 145-164
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Tidskriftsartikel (refereegranskat)abstract
- A methodology based on inverse modelling for estimating viscoplastic material parameters at high strain-rate conditions is presented. The methodology is demonstrated for a mild steel exposed for compression loading in a split Hopkinson pressure bar arrangement. By using dog-bone shaped specimens nonhomogeneous states of deformation are obtained throughout the entire deformation process. The resulting nonhomogeneous deformation of the specimens is evaluated using digital speckle photography (DSP) to give in-plane point-wise displacement and strain fields. The photographs are captured with a high-speed camera of image converter type, which acquire time resolved images during the impact loading. The experiments are simulated using finite element analysis (FEA), where the material model suggested by Johnson-Cook for high-strain rate conditions are utilised. Experimental and FE-calculated field information are compared in order to estimate the viscoplastic parameter in the Johnson-Cook material model. The estimation is performed by minimising least-square functions that contain the differences in displacements and strains, respectively. The quality of the estimated parameters is studied from statistical point of view.
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| 7. |
- Oldenburg, Mats, et al.
(författare)
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A friction model for iron powder pressing based on a tribological approach
- 1996
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Ingår i: Advances in powder metallurgy & particulate materials - 1996. - Princeton, NJ : Metal powder industries federation. - 1878954598 ; , s. 329-340
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Konferensbidrag (refereegranskat)abstract
- The global behaviour of the cold pressing process of iron powder is dependent on the material response in the powder as well as the friction between the powder and the tool walls. Both the behaviour with respect to the material response and the friction effects are dependent on the lubricant used in the powder mixture. Normally, solid phase lubricants are mixed into the iron powder. It is assumed that the local heat generated in the microscopic contact areas between the powder and the tool walls is partly responsible for the functionality of the lubricant. The microscopic interaction between powder, lubricant and tool wall at the point of contact is described by relations between the friction coefficient and a combination of state variables, e.g. relative velocity, pressure and powder density. The relations are established by use of tribological classifications of the lubricant as well as the mixture of lubricant and iron powder. Finite element simulations of pressing experiments are used for studying the influence of the frictional relations on the global pressing behaviour.
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| 8. |
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| 9. |
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| 10. |
- Oldenburg, Mats, et al.
(författare)
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Study of metal powder component pressing with use of numerical simulations
- 1998
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Ingår i: Proceedings of the 1998 powder metallurgy world congress and exhibition. - Shrewsbury : European powder metallurgy association. - 1899072098 ; , s. 2.51-2.56
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Konferensbidrag (refereegranskat)abstract
- The global behaviour of the cold pressing process of iron powder is dependent on the process kinematics, material response in the powder as well as the friction effects in the contact between the powder and the tool walls. The analysis of powder pressing requires accurate material models of the various powder mixes that are used. The modelling is dependent on tri-axial compression tests for the material model and friction tests for the nonlinear friction model. The modelling parameters have been determined in international cooperation within the COST 512 and MMPF (Modelling of Metal Powder Forming) research programs. Component pressing with varying kinematic conditions have been performed by the Sintertech company. In this work, a set of process and model parameters have been established for numerical simulations of powder pressing process.
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