№82-15

Theoretical substantiation of effective fracture toughness in metallic alloys of cylindrical shells

S. Fedoriachenko¹, https://orcid.org/0000-0002-8512-3493

K. Ziborov¹,             https://orcid.org/0000-0002-4828-3762

D. Laukhin¹,            https://orcid.org/0000-0002-9842-499X

V. Korol^1,2,              https://orcid.org/0009-004-6433-1797

D. Harkavenko¹       https://orcid.org/0009-0004-5011-9015

¹ Dnipro University of Technology, Dnipro, Ukraine

² Metinvest Engineering, Dnipro, Ukraine

Coll.res.pap.nat.min.univ. 2025, 82:175-182

Full text (PDF)

https://doi.org/10.33271/crpnmu/82.175

ABSTRACT

Purpose. To establish the relationship between the microstructural features of cast materials, specifically porosity, segregation, grain size, and non-metallic inclusions and effective fracture toughness under high-velocity dynamic loading by determination of theoretical dependencies for calculating effective fracture toughness under defined parameters of macroscopic defects in the material.

Methodology. A combined analytical–numerical approach was applied to model the dynamic response of cylindrical shells under high-velocity loading, implemented through a system of dynamic differential equations that account for material quality criteria and the principles of linear elastic fracture mechanics.

Findings. A methodology for assessing the quality of cast materials has been developed based on an integrated mechanical–mathematical model and the principles of linear fracture mechanics. Quantitative relationships for evaluating crack initiation resistance were obtained with consideration of the microstructural characteristics of the material. The correlation between the crack initiation criterion and the critical defect size was established.

Originality. For the first time, a comprehensive approach is proposed to predict the behavior of cast cylindrical shells based on a mechanical–mathematical crack formation model incorporating internal defects. Relationships were established between the microstructural characteristics of metallic alloys-such as porosity, grain size, and non-metallic inclusions – and effective fracture toughness, enabling the formalization of conditions governing the transition from a local defect to a critical crack size. A methodology was proposed for quantitative reproduction of porosity- and cracking-risk zones, adapted to specific alloy compositions and casting technologies.

Practical value. The obtained results provide a scientifically grounded basis for optimizing casting processes of cylindrical shells with specified performance properties. The proposed methodology enables determination of permissible ranges of microstructural parameters, ensuring controlled fracture toughness and predictable service life of the structures.

Keywords: metal alloy, crack formation, microstructural heterogeneity, porosity, casting defects.

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