Käßmair, Stefan, Dr.-Ing.
Dr.-Ing. Stefan Käßmair
Zur Formulierung und zum mikromechanischen Ursprung von Diffusionsmodellen
(Drittmittelfinanzierte Einzelförderung)
Projektleitung:
Projektstart: 1. Juli 2012
Projektende: 31. Juli 2019
Mittelgeber: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
Abstract:
Diffusion, especially when coupled with deformation, is of utmost scientific and technological im-portance in various fields of engineering, materials science, natural sciences and their intersections. Prominent examples are the modelling and simulation of solder joints, micro-structure evolution in advanced materials as used e.g. in modern and future turbine blades produced from single crystals, mineral unmixing in geology, contaminant distribution in environmental systems, and drug transport and delivery in biological tissues. In many of these instances classical diffusion models of Fick-type do not accurately describe the observed phenomena, thus requiring non-classical diffusion models. Specific examples for non-classical models of diffusion are the Cahn-Hillard equation and Gurtin's microforce balance.The long-term goals of this project are therefore (i) the formulation and simulation of a generic class of non-classical three-dimensional models of diffusion, (ii) the exploration of their micromechanical origin and (iii) their coupling to deformation. Thereby it is noted that gradient-type and micromorphic-type models as paradigms of extended continuum models are intimately related and offer different benefits and drawbacks2. Thus, as a mid-term goal, gradient-type and micromorphictype formulations of diffusion shall be considered alternatively in Phase I. In order to explore their micromechanical origin, relevant response quantities that participate in the corresponding field equations at the macro-level shall be determined from the micro-level by a second-order computational homogenization.The expected output of this project in Phase I is thus the clarification of the underlying micromechani-cal origin of a generic class of non-classical models of diffusion. Phase II will then concentrate mainly on the coupling of diffusion and deformation. The overall outcome of the project will be of great im-portance in various fields such as engineering, materials science and natural sciences from both the scientific and the technological view point. In particular the design and understanding in the area of novel and advanced materials will be strongly enhanced by the expected findings of this project.
2016
Proposal for an Improved Engineering Fatigue Lifetime Assessment Concept
Pressure Vessels and Piping Conference (Vancouver, 17. Juli 2016 - 21. Juli 2016)
In: American Society of Mechanical Engineers (Hrsg.): Proceedings of the ASME 2016 Pressure Vessels & Piping Conference 2016
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Effects of Boiling Water Reactor Medium on the Fatigue Life of Austenitic Stainless Steels
In: Journal of Pressure Vessel Technology-Transactions of the Asme 138 (2016), S. 031406-1 - 031406-6
ISSN: 0094-9930
DOI: 10.1115/1.4032651
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The Effect of Heat Treatments at Different Plastic States on the Isotropic Hardening Behavior of Austenitic Stainless Steel
Annual Meeting on Nuclear Technology (Hamburg, 10. Mai 2016 - 12. Mai 2016)
In: Compacts of the 47th AMNT 2016
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2015
Experimental Investigations on Environmentally Assisted Fatigue of Ferritic and Austenitic Materials Including Dissimilar Metal Welds
Materials Testing Institute University of Stuttgart - Seminar (Stuttgart, 5. Oktober 2015 - 6. Oktober 2015)
In: Materialprüfungsanstalt der Universität Stuttgart (Hrsg.): Manuscripts of the 41th MPA Seminar 2015
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Effects of Pressurized Water Reactor Medium on the Fatigue Life of Austenitic Stainless Steels
In: Journal of Pressure Vessel Technology-Transactions of the Asme 137 (2015), S. 061404-1 - 061404-7
ISSN: 0094-9930
DOI: 10.1115/1.4029832
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Fatigue Approach for Addressing Environmental Effects in Fatigue Usage Calculation
In: Atw-International Journal For Nuclear Power 60 (2015), S. 245 - 250
ISSN: 1431-5254
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Fatigue Strain-Life Behavior of Austenitic Stainless Steels in Pressurized Water Reactor Environments
Pressure Vessels and Piping Conference (Boston, 19. Juli 2015 - 23. Juli 2015)
In: American Society of Mechanical Engineers (Hrsg.): Proceedings of the ASME 2015 Pressure Vessels & Piping Conference 2015
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Statistical Analysis of Fatigue Data for Austenitic Stainless Steels in Water Environments
Annual Meeting on Nuclear Technology (Berlin, 5. Mai 2015 - 7. Mai 2015)
In: Compacts of the 46th AMNT 2015
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Statistical Models for Estimating Fatigue Lives of Austenitic Stainless Steels in Light Water Reactor Environments
Structural Mechanics in Reactor Technology (Manchester, 10. August 2015 - 14. August 2015)
In: Compacts of the 23th SMiRT Conference 2015
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2014
Environmental Influences on the Fatigue Assessment of Austenitic and Ferritic Steel Components Including Welds
Pressure Vessels and Piping Conference (Anaheim, 20. Juli 2014 - 24. Juli 2014)
In: American Society of Mechanical Engineers (Hrsg.): Proceedings of the ASME 2014 Pressure Vessels & Piping Conference 2014
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Recent Amendments of EN13445-3, Clause 18 and Related Annexes: Detailed Assessment of Fatigue Life
Pressure Vessels and Piping Conference (Anaheim, 20. Juli 2014 - 24. Juli 2014)
In: American Society of Mechanical Engineers (Hrsg.): Proceedings of the ASME 2014 Pressure Vessels & Piping Conference 2014
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Compilation of Fatigue Data for Austenitic Stainless Steels
Annual Meeting on Nuclear Technology (Frankfurt am Main, 6. Mai 2014 - 8. Mai 2014)
In: Compacts of the 45th AMNT 2014
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Discussion of Fatigue Data for Austenitic Stainless Steels
Pressure Vessels and Piping Conference (Anaheim, 20. Juli 2014 - 24. Juli 2014)
In: American Society of Mechanical Engineers (Hrsg.): Proceedings of the ASME 2014 Pressure Vessels & Piping Conference 2014
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Einbindung der neuen Regelwerksanforderungen in lokale Fatigue-Monitoring Lösungen
Workshop of Materials Testing Institute University of Stuttgart: „Ermüdungsverhalten von Bauteilen in Leichtwasserreaktoren unter Berücksichtigung des Kühlmediums“ (Stuttgart, 10. September 2014 - 10. September 2014)
In: Materialprüfungsanstalt der Universität Stuttgart (Hrsg.): MPA Workshop 2014: Ermüdungsverhalten 2014
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Statistical Model of Water Environment Effects on the Fatigue Behavior of Austenitic Stainless Steels
Materials Testing Institute University of Stuttgart - Seminar (Stuttgart, 6. Oktober 2014 - 7. Oktober 2014)
In: Materialprüfungsanstalt der Universität Stuttgart (Hrsg.): Manuscripts of the 40th MPA Seminar 2014
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2013
Guidelines for Addressing Environmentally Assisted Fatigue in Fatigue Usage Calculation and Further Recommendations
Annual Meeting on Nuclear Technology (Berlin, 14. Mai 2013 - 16. Mai 2013)
In: Compacts of the 44th AMNT 2013
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Study on Fatigue Analysis for Operational Load Histories
Materials Testing Institute University of Stuttgart - Seminar (Stuttgart, 8. Oktober 2013 - 9. Oktober 2013)
In: Materialprüfungsanstalt der Universität Stuttgart (Hrsg.): Manuscripts of the 39th MPA Seminar 2013
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