Browsing by Author "Frolov, Yaroslav V."

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    Kirigami Inspired Solid-State Alloying (KISA) Method of Creation of Functionally Graded Materials
    (Український державний університет науки і технологій, ІВК «Системні технології», Дніпро, 2025) Frolov, Yaroslav V.; Bobukh, Oleksandr S.; Boiarkin, V. V.; Konovodov, Dmytro V.
    ENG: Kirigami-inspired solid-state alloying (KISA) is an innovative technique that applies kirigami principles to control the distribution of alloying elements within a matrix during pressure bonding. By employing precise cuts and patterns, KISA manipulates diffusion and precipitate formation at micro- and nanoscale levels, leading to tailored material properties. This method eliminates challenges associated with conventional liquid alloying, such as oxidation and element loss, while enabling controlled microstructure evolution through roll bonding and heat treatment. Key advantages include improved phase distribution, enhanced interfacial properties, and adaptability for various material types, including powders and amorphous substances. KISA presents new opportunities for designing functionally graded materials with customized mechanical, electrical, and thermal characteristics.
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    Patterning of Surfaces for Subsequent Roll Bonding in a Low-Oxygen Environment Using Deformable Mesh Inlays
    (MDPI, 2023) Frolov, Yaroslav V.; Bobukh, Oleksandr S.; Samsonenko, Andrii A.; Nürnberger, Florian
    ENG: Efficient roll bonding for the manufacturing of clad strips not only requires surface activation but also is improved by a surface patterning to reduce the initial contact area. This increases contact stresses and facilitates a joining without an increasing rolling force. Experiments to pattern surfaces with deformable inlays during cold rolling for a subsequent bonding in low-oxygen atmosphere were carried out using two types of rolling mills, two types of inlays and two types of assemblies. Digital twins of selected experiments were created by means of the FE simulation software QForm UK 10.2.4. The main set of rolling parameters, which play a significant role during formation of the pattern shape considering deformation of the patterning tool, were investigated. The pilot roll bonding of patterned components under vacuum conditions, provided using vacuum sealer bags, allowed for an experimental realization of this approach. The concept technological chain of roll bonding in a low-oxygen or oxygen-free environment comprises the following stages: roll patterning; surface activation and sealing of the strips in a vacuum bag; subsequent roll bonding of the prepared strips inside the protective bag. The difference between the shape of the pattern created and the initial shape of the mesh insert can be quantitatively described by the change of its angle. This difference reaches maximum values when smaller rolls are used with increased rolling reductions. This maximum value is limited by the springback of the deformed insert; the limit is reached more easily if the inlay is not positioned on the rolling plane.
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    Transformation of the Kirigami-Type Deformable Inlay during Roll Bonding
    (Dnipro University of Technology, Dnipro, 2025) Frolov, Yaroslav V.; Konovodov, Dmytro V.; Bobukh, Oleksandr S.; Boiarkin, V.
    ENG: Purpose. To quantitatively analyze the deformation of kirigami-type deformable inlays during the roll bonding process using soft outer matrices, with the goal of predicting their behavior within the composite structure. Methodology. The research involved the fabrication of three-layer composite sheets through roll bonding. Expanded meshes made of mild steel and stainless steel served as the inlay phase, while copper and aluminum alloy sheets were employed as matrix materials. The transformation of the inlay phase within the composite sheets was evaluated. Findings. The experimental investigation yielded data on the deformation behavior of kirigami-type inlays embedded within three-layer sheets during roll bonding. It was observed that using an aluminum matrix induces greater axial metal flow in the deformation zone, leading to a significant increase in the mesh distortion angle. A copper matrix primarily causes flattening of the mesh cells with minimal changes to their angular deformation. In contrast, rolling the steel mesh without a matrix results in negligible angular distortion until the rolling reduction exceeds 50 %. Originality. This study represents the first quantitative analysis of the geometric transformation of kirigami-type deformable inlays as a function of deformation magnitude and matrix material properties during roll bonding. Understanding the shape transformation of the reinforcing phase within the composite sheet enables more accurate prediction of the contact area between the matrix materials during the bonding process. Practical value. The findings of this research provide a basis for predicting the final geometry of kirigami structures within composite materials.