Browsing by Author "Movchan, Oleksandr Yu."

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Advanced Damage‑Plasticity Modelling and Calibration Strategies for Accurate Finite‑Element Analysis of Unreinforced Concrete in Thin‑Walled Structures
(Український державний університет науки і технологій, ІВК «Системні технології», Дніпро, 2025) Movchan, Oleksandr Yu.
ENG: Accurate finite‑element representation of unconventional concretes – slag‑blended, recycled‑aggregate, fiber‑reinforced, or ultra‑thin formwork mixes requires more than the legacy smeared‑crack tools that still dominate industrial workflows. This theses reviews research on 3D material modelling of plain, fiber‑ and aggregate‑modified concretes in the ANSYS environment, with emphasis on constitutive law selection, experimental calibration, and numerical tactics that preserve convergence once cracking and crushing initiate. Damage‑plasticity formulations such as Concrete Damaged Plasticity (CDP) consistently outperform simpler Drucker–Prager or Willam–Warnke approaches, provided their numerous parameters are tuned to targeted laboratory data. Special issues arising in thin‑walled elements and permanent formwork stability, mesh objectivity, staged casting pressure are examined, and five recent case studies are dissected to illustrate best practice. The review concludes with recommendations for practitioners and identifies emerging trends, notably machine‑learning‑assisted calibration and phase‑field fracture, that are poised to reshape concrete simulation in commercial FEA.
Advanced Damage-Plasticity Modelling and Calibration Strategies for Accurate Finite-Element Analysis of Unreinforced Concrete in Thin-Walled Structures
(Український державний університет науки і технологій, ННІ ≪Дніпровський металургійний інститут≫, ІВК ≪Системні технології≫, Дніпро, 2025) Movchan, Oleksandr Yu.
ENG: Accurate prediction of unconventional, unreinforced concretes in three‑dimensional finite‑element analysis demands a synthesis of advanced constitutive theory, rigorous experimental calibration, and careful numerical implementation. This study consolidates recent progress and remaining challenges in modeling slag‑blended, recycled‑aggregate, fiber‑reinforced, and ultra‑thin formwork concretes within the ANSYS environment. A literature survey identifies three dominant strategies for plain concrete: the legacy smeared‑crack SOLID65 element, generalized Drucker–Prager plasticity with user‑defined damage, and detailed mesoscale representations that resolve aggregates, mortar, and inter-faces. Comparative findings show that damage‑plasticity formulations, exemplified by the Concrete Damaged Plasticity (CDP) model, reproduce load–deflection responses and crack patterns within fifteen percent of experimental results when parameters are calibrated against comprehensive test sets that include compression, tension, fracture, and time‑dependent data. Calibration protocols remain inconsistent across studies, hindering reproducibility and cross‑comparison. The absence of an open benchmark database for non‑standard concretes is highlighted as a key barrier to consensus on default parameters. Thin‑walled elements expose additional difficulties: geometric nonlinearity couples with progressive stiffness degradation, causing mesh‑dependent fracture energy dissipation and solver convergence issues. Remedies include refined through‑thickness meshes, nonlocal regularization, and robust arc‑length solution controls. Explicit crack‑tracking techniques such as phase‑field fracture and cohesive segments offer improved fidelity, especially for fiber‑rich mixes where residual tensile capacity governs serviceability, yet systematic validation of these methods remains sparse. Long‑term phenomena such as creep, shrinkage, and durability, along with high‑rate behaviors under impact and seismic loading, are underrepresented in current model verification, particularly for slag‑rich and recycled‑aggregate mixes. A practical roadmap is proposed that integrates five core actions: creation of a public benchmark database with fully documented laboratory tests; development of unified modeling protocols that specify calibration sequences, error metrics, and reporting formats; targeted investment in explicit fracture models for thin and fiber‑reinforced members; expansion of long‑term and dynamic experimental programs; and adoption of machine‑learning tools to automate parameter identification and flag anomalous model behavior. Complementary software advances, including plug‑and‑play material subroutines and graphical calibration wizards, are recommended to lower the expertise threshold for practicing engineers. Collectively, these measures chart a pathway from current academic advances toward robust, industry‑ready simulations capable of guiding the design of sustainable, reinforcement‑free concrete structures.