| 1. |
- Ruggiero, Andrew, et al.
(författare)
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Deformation and Failure of OFHC Copper under high strain rate shear compression
- 2017
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Ingår i: AIP Conference Proceedings. - : Author(s). - 1551-7616 .- 0094-243X. - 9780735414570 ; 1793
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Konferensbidrag (refereegranskat)abstract
- Hat-shaped specimen geometries were developed to generate high strain, high-strain-rates deformation under prescribed conditions. These geometries offer also the possibility to investigate the occurrence of ductile rupture under low or negative stress triaxiality, where most failure models fail. In this work, three tophat geometries were designed, by means of extensive numerical simulation, to obtain desired stress triaxiality values within the shear region that develops across the ligament. Material failure was simulated using the Continuum Damage Model (CDM) formulation with a unilateral condition for damage accumulation and validated by comparing with quasi-static and high strain rate compression tests results on OFHC copper. Preliminary results seem to indicate that ductile tearing initiates at the specimen corner location where positive stress triaxiality occurs because of local rotation and eventually propagates along the ligament.
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| 2. |
- Testa, Gabriel, et al.
(författare)
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Modelling and simulation of dynamic recrystallization (DRX) in OFHC copper at very high strain rates
- 2017
-
Ingår i: AIP Conference Proceedings. - : Author(s). - 1551-7616 .- 0094-243X. - 9780735414570 ; 1793, s. Article number 100034-
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Konferensbidrag (refereegranskat)abstract
- At high strain rates, deformation processes are essentially adiabatic and if the plastic work is large enough dynamic recrystallization can occur. In this work, an examination on microstructure evolution of OFHC copper in Dynamic Tensile Extrusion (DTE) test, performed at 400 m/s, was carried out. EBSD investigations, along the center line of the fragment remaining in the extrusion die, showed a progressive elongation of the grains, and an accompanying development of a strong + dual fiber texture. Discontinuous dynamic recrystallization (DRX) occurred at larger strains, and it was showed that nucleation occurred during straining. A criterion for DRX to occur, based on the evolution of Zener-Hollomon parameter during the dynamic deformation process, is proposed. Finally, DTE test was simulated using the modified Rusinek-Klepaczko constitutive model incorporating a model for the prediction of DRX initiation.
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