Saketh Virupakshi, MSc

Department of Mechanics of Materials (ZMM)
Division of Micromechanics of Materials (PMM)
position: Specialist
telephone: (+48) 22 826 12 81 ext.: 436
room: 138
e-mail: svirupak

Recent publications
1.Virupakshi S., Kowalczyk-Gajewska K., Cylindrical void growth vs. grain fragmentation in FCC single crystals: CPFEM study for two types of loading conditions, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2023.112397, Vol.280, pp.112397-1-112397-19, 2023
Abstract:

The crystal plasticity finite element method (CPFEM) is used to investigate the coupling between the cylindrical void growth or collapse and grain refinement in face-centred cubic (FCC) single crystals. A 2D plane strain model with one void is used. The effect of the initial lattice orientation, similarities, and differences between stress- and strain-driven loading scenarios are explored. To this end, boundary conditions are enforced in two different ways. The first one is based on maintaining constant in-plane stress biaxiality via a dedicated truss element, while the second one is imposing a constant displacement biaxiality factor. Uniaxial and biaxial loading cases are studied. For the uniaxial loading case a special configuration, which enforces an equivalent pattern of plastic deformation in the pristine crystal, is selected in order to investigate the mutual interactions between the evolving void and the developed lattice rotation heterogeneity. Next, biaxial loading cases are considered for three crystal orientations, one of which is not symmetric with respect to loading directions. It is analysed how stress or strain biaxility factors and initial lattice orientation influence the void evolution in terms of its size and shape. Moreover, the consequences of variations in the resulting heterogeneity of lattice rotation are studied in the context of the grain refinement phenomenon accompanying the void evolution. Scenarios that may lead to more advanced grain fragmentation are identified.

Keywords:

Crystal plasticity , Finite element method, Void evolution, Grain refinement

Affiliations:
Virupakshi S.-IPPT PAN
Kowalczyk-Gajewska K.-IPPT PAN
2.Frydrych K., Jarzębska A., Virupakshi S., Kowalczyk-Gajewska K., Bieda M., Chulist R., Skorupska M., Schell N., Sztwiernia K., Texture-based optimization of crystal plasticity parameters: application to zinc and its alloy, METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, ISSN: 1073-5623, DOI: 10.1007/s11661-021-06285-7, Vol.52, No.8, pp.3257-3273, 2021
Abstract:

Evolutionary algorithms have become an extensively used tool for identification of crystal plasticity parameters of hexagonal close packed metals and alloys. However, the fitness functions were usually built using the experimentally measured stress–strain curves. Here, the fitness function is built by means of numerical comparison of the simulated and experimental textures. Namely, the normalized texture difference index is minimized. The evolutionary algorithm with the newly developed fitness function is tested by performing crystal plasticity parameter optimization for both pure zinc and zinc-magnesium alloy. These materials are promising candidates for bioabsorbable implants due to good biocompatibility and optimal corrosion rate. Although their mechanical properties in the as-cast state do not fulfill the requirements, they can be increased by means of hydrostatic extrusion. The developed modeling approach enabled acquisition of the crystal plasticity parameters and analysis of the active deformation mechanisms in zinc and zinc-magnesium alloy subjected to hydrostatic extrusion. It was shown that although slip systems are the main deformation carrier, compressive twinning plays an important role in texture evolution. However, the texture is also partially affected by dynamic recrystallization which is not considered within the developed framework.

Affiliations:
Frydrych K.-IPPT PAN
Jarzębska A.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Virupakshi S.-IPPT PAN
Kowalczyk-Gajewska K.-IPPT PAN
Bieda M.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Chulist R.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)
Skorupska M.-Institute of High Pressure Physics, Polish Academy of Sciences (PL)
Schell N.-other affiliation
Sztwiernia K.-Institute of Metallurgy and Materials Science, Polish Academy of Sciences (PL)

Conference abstracts
1.Kowalczyk-Gajewska K., Virupakshi S., Evolution of Lattice Orientation Heterogeneity in HCP Single Crystals Due to Void Growth, IUTAM Symposium, IUTAM Symposium on Enhancing Material Performance by Exploiting Instabilities and Damage Evolution, 2022-06-05/06-10, Warszawa (PL), DOI: 10.24423/iutam2022warsaw, No.P014, pp.27-27, 2022
2.Virupakshi S., Frydrych K., Kowalczyk-Gajewska K., Effect of Boundary Conditions and Crystallographic Orientation on the Cylindrical Void Growth in FCC Single Crystals Using CPFEM, IUTAM Symposium, IUTAM Symposium on Enhancing Material Performance by Exploiting Instabilities and Damage Evolution, 2022-06-05/06-10, Warszawa (PL), DOI: 10.24423/iutam2022warsaw, No.P043, pp.57-57, 2022