| 1. |
- Babu, Bijish, Tec. Lic. 1979-, et al.
(författare)
-
Physically Based Constitutive Model of Ti-6Al-4V for Arbitrary Phase Composition
- 2018
-
Ingår i: International journal of plasticity. - 0749-6419 .- 1879-2154.
-
Tidskriftsartikel (refereegranskat)abstract
- The principal challenge in producing aerospace components using Ti-6Al-4V alloy is to employ the optimum process window of deformation rate and temperature to achieve desired material properties. Qualitatively understanding the microstructure-property relationship is not enough to accomplish this goal. Developing advanced material models to be used in manufacturing process simulation is the key to compute and optimize the process iteratively. The focus in this work is on physically based flow stress models coupled with microstructure evolution models. Such a model can be used to simulate processes involving complex and cyclic thermo-mechanical loading.
|
|
| 2. |
- Brown, Richard J. P., et al.
(författare)
-
Liver-expressed Cd302 and Cr1l limit hepatitis C virus cross-species transmission to mice
- 2020
-
Ingår i: Science Advances. - : American Association for the Advancement of Science. - 2375-2548. ; 6:45
-
Tidskriftsartikel (refereegranskat)abstract
- Hepatitis C virus (HCV) has no animal reservoir, infecting only humans. To investigate species barrier determinants limiting infection of rodents, murine liver complementary DNA library screening was performed, identifying transmembrane proteins Cd302 and Cr1l as potent restrictors of HCV propagation. Combined ectopic expression in human hepatoma cells impeded HCV uptake and cooperatively mediated transcriptional dysregulation of a noncanonical program of immunity genes. Murine hepatocyte expression of both factors was constitutive and not interferon inducible, while differences in liver expression and the ability to restrict HCV were observed between the murine orthologs and their human counterparts. Genetic ablation of endogenous Cd302 expression in human HCV entry factor transgenic mice increased hepatocyte permissiveness for an adapted HCV strain and dysregulated expression of metabolic process and host defense genes. These findings highlight human-mouse differences in liver-intrinsic antiviral immunity and facilitate the development of next-generation murine models for preclinical testing of HCV vaccine candidates.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Charles, Corinne, 1979-
(författare)
-
Modelling microstructure evolution of weld deposited Ti-6Al-4V
- 2008
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The microstructure and consequently the mechanical properties of titanium alloys are highly dependent on the temperature history endured by the material. The manufacturing process of metal deposition induces repetitive cooling and heating in the material determining a specific microstructure. The presented study is devoted to developing and implementing a microstructure model for Ti-6Al-4V intended to be coupled to a thermo- mechanical model of the metal deposition process.Microstructural analysis of the metal deposited samples was first performed to understand the formed microstructure. A set of representative parameters for microstructure modelling were then selected as representative for the known impact of Ti-6Al-4V microstructure on mechanical properties. Evolution equations for these parameters were implemented for thermal finite element analysis of the process. Six representative state variables are modelled: the phase volume fraction of total alpha, beta, Widmanstätten alpha, grain boundary alpha, martensite alpha, and the alpha lath thickness. Heating, cooling and repeated re-heating involved in the process of metal deposition are taken into account in the model. The phase transformations were modelled based on a diffusionnal theory described by a Johnson-Mehl-Avrami formulation, as well as diffusionless transformations for the martensite alpha formation and the beta reformation during reheating. The Arrhenius equation is applied as a simplification to model temperature dependent alpha lath size calculation. Grain growth is not included in the present formulation, but would have to be added for capturing alpha lath coarsening during long term heat treatment.The temperature history during robotised tungsten inert gas deposition welding is simulated together with the microstructure. The implementation of the model handles well the complex cyclic thermal loading from the metal deposition process. A particular banded structure observed in the metal deposited microstructure is partially explained using the proposed microstructure model. It is concluded that although qualitatively interesting results have been achieved, further calibration testing over a wider range of temperature histories must be performed to improve the transformation kinetic parameters for reliable quantitative predictions of the microstructure.
|
|
| 7. |
|
|
| 8. |
- Charles Murgau, Corinne, 1979-, et al.
(författare)
-
A model for Ti-6Al-4V microstructure evolution for arbitrary temperature changes
- 2012
-
Ingår i: Modelling and Simulation in Materials Science and Engineering. - : IOP Publishing. - 0965-0393 .- 1361-651X. ; 20:5, s. 055006-
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a microstructure model for the titanium alloy Ti-6Al-4V designed to be used in coupled thermo-metallurgical-mechanical simulations of, e.g., welding processes. The microstructure evolution is increasingly taken into consideration in analyses of manufacturing processes since it directly affects the mechanical properties. Thermally driven phase evolutions are accounted for in the model. A state variable approach is adopted to represent the microstructure with the objective to integrate the microstructure changes with a thermomechanical model of manufacturing process simulation such as welding. The model is calibrated using the literature data and also validated against a cyclic temperature history during multi-pass welding.
|
|
| 9. |
|
|
| 10. |
|
|
