| 1. |
- Andersson, Daniel, et al.
(författare)
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Determination of yield surfaces in advanced constitutive powder models using inverse modeling
- 2011
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Ingår i: Proceedings of the Euro PM 2011 Congress and Exhibition. - : European Powder Metallurgy Association. - 9781899072200 ; , s. 247-252
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Konferensbidrag (refereegranskat)abstract
- In order to decrease the extensive experimental work in product development of WC/Co powder tooling equipment, an investigation of the applicability of inverse procedures to industrially relevant material models is performed. The powder die compaction process of WC/Co powder is modeled using the finite element method and an advanced plasticity-based constitutive model. An angled indenter is used to increase the sensitivity of constitutive parameters with respect to the measurable data from experiment, which is done using an instrumented die. Here, the inverse modeling (optimization) is performed (using iterative reduction of variable space and a combination of genetic (GA) and gradient search algorithms) in order to determine the yield surface of the investigated material. The results indicate that inverse modeling can be a useful tool in order to reduce the experimental efforts at material characterization of powder materials described by advanced material models.
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| 2. |
- Frisk, Karin, et al.
(författare)
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Oxygen in pilot-scale gas atomised powders - Study of oxygen uptake and oxide characterisation
- 2011
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Ingår i: Proceedings of the Euro International Powder Metallurgy Congress and Exhibition, Euro PM 2011. - : European Powder Metallurgy Association (EPMA). - 9781899072200
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Konferensbidrag (refereegranskat)abstract
- Properties of steel are detrimentally affected by oxygen and the content should be minimised. The effect of oxygen on steel properties depends on the type of steel, on the amount of dissolved oxygen and on the type and size of oxides, and on microstructure. In steel produced from powder, surface oxides on the powder grains, dissolved oxygen as well as oxide inclusions originating from the melt contribute to the total oxygen content. It is therefore interesting to investigate under what conditions oxygen uptake takes place, and how oxides are formed and can be characterised. A lab scale atomizer with a maximum charge weight of approximately 10 kg has been used. Powder atomisations have been performed, using an oxysensor to monitor the oxygen levels at different positions in the atomisation equipment, and melt samples have been extracted. Oxygen in the powder is characterised using Photo Acoustic Spectroscopy (PAS), by analysing oxygen contents in powder and in compacted samples, and by microstructure investigations.
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| 3. |
- Olsson, Erik, et al.
(författare)
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Effect of particle size distribution at powder compaction
- 2011
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Ingår i: Proceedings of the Euro International Powder Metallurgy Congress and Exhibition, Euro PM 2011. - : European Powder Metallurgy Association (EPMA). - 9781899072200 ; , s. 265-270
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Konferensbidrag (refereegranskat)abstract
- The Discrete Element Method (DEM) has been used to investigate the effects of particle size distribution during closed die compaction of powders. In the simulations, the effect of considering rotational degrees of freedom in the analysis is studied. Both loading and unloading of the powder compound is investigated and the particle size distribution is assumed to be a truncated normal distribution. The powder particles are assumed rigid plastic in compression and following Hertz elastic contact law during unloading. From a convergence study, it was found that 4000 particles were sufficient to represent the global properties of the powder compact. Among other things, the results show that when the size of the particles does not deviate considerably from the average size, the effect on global compaction properties is basically negligible.
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