1. A multiscale approach to deformation and fracture of heat-resistant steel under static and cyclic loadingP. O. Maruščak, Denys Baran, Vladimir Gliha, 2013, original scientific article Abstract: Regularities of static and cyclic deformation, damage and fracture of heat-resistant steel 25Kh1M1F, based on the approaches of physical mesomechanics and 3D interferometry method, are presented in this paper. The applicability of these techniques for different hierarchy levels of deformation was studied. The investigation of scanning microscope photos was conducted for several dissipative structures, fragmentation of the material, localisation of macrodeformation and subsequent failure on macro- and mesolevel. It is shown that the used modern techniques of experimental analysis are very efficient in understanding deformation and damage evolution in materials.
Keywords: fracture, heat-resistant steel, cyclic loading, fatigue, plastic deformation
Published in DKUM: 18.08.2017; Views: 1005; Downloads: 330
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2. Deformation and energy parameters of fracture of steel of the main gas pipelineP. O. Maruščak, Sergey Panin, Ulyana Polyvana, Tomaž Vuherer, Anna Guzanová, Janette Brezinová, 2015, original scientific article Abstract: By example of steel 17G1S, the regularities in the impact fracture of Charpy specimens at normal and low temperatures are described. The relationship between the energy parameters of fracture (impact toughness) and the deformation response of the material (the height of shear lips) of the specimens from the pipe steel is established. The micromechanisms of impact fracture of the material are described. At 20 °C and –30 °C, focal splitting of the material was observed on the fracture surface of specimens; at –60 °C, the material failed in a brittle manner by the mechanism of cleavage.
Keywords: impact toughness, main gas pipeline, failure analysis
Published in DKUM: 08.08.2017; Views: 880; Downloads: 357
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3. Low temperature impact toughness of the main gas pipeline steel after long-term degradationP. O. Maruščak, Irina Danyliuk, R.T. Biščak, Tomaž Vuherer, 2014, original scientific article Abstract: The correlation of microstructure, temperature and Charpy V-notch impact properties of a steel 17G1S pipeline steel was investigated in this study. Within the concept of physical mesomechanics, the dynamic failure of specimens is represented as a successive process of the loss of shear stability, which takes place at different structural/scale levels of the material. Characteristic stages are analyzed for various modes of failure, moreover, typical levels of loading and oscillation periods, etc. are determined. Relations between low temperature derived through this test, microstructures and Charpy (V-notch) toughness test results are also discussed in this paper.
Keywords: impact toughness, fracture, damage, gas pipeline, steel, degradation
Published in DKUM: 03.04.2017; Views: 1051; Downloads: 402
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4. Physical regularities in the cracking of nanocoatings and a method for an automated determination of the crack-network parametersP. O. Maruščak, Vladimir Gliha, Igor Konovalenko, Tomaž Vuherer, Sergey Panin, 2012, professional article Abstract: The regularities and spatial distribution of multiple cracking of a nanocoating are investigated. It is found that in the cracking zones the relaxation of the stresses accumulated in the coating takes place; moreover, the intensity of its failure is determined by the structural level of defect accumulation. A new algorithm for a digital identification of the elements of a crack network in a nanocoating is proposed, and its adequacy is checked.
Keywords: nanocoatings, cracks, materials testing
Published in DKUM: 10.07.2015; Views: 907; Downloads: 108
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5. Behaviour of short cracks emanating from tiny drilled holesVladimir Gliha, P. O. Maruščak, Tomaž Vuherer, 2013, original scientific article Abstract: Specimens with martensitic microstructure were defected by tiny drilled holes with the existing local residual stresses induced by drilling and without them. The objective of this research was to determine the cyclic stress level for the crack initiation and fatigue limit of the defected and smooth specimens' dependence upon the residual-stress field. Compressive residual stresses retarded the crack initiation. Immediately after the crack initiation, residual stresses decelerated the short-crack propagation, but later, when the residual-stress sign was changed, they accelerated it. Non-propagating short-crack size and fatigue limit also depend on the residual-stress field.
Keywords: small defect, drilled hole, crack initiation, crack propagation, short crack, long crack, anomalous fast-crack propagation
Published in DKUM: 10.07.2015; Views: 1055; Downloads: 108
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6. Automated diagnostics of damage to an aluminum alloy under the conditions of high-cycle fatigueP. O. Maruščak, Igor Konovalenko, Mykhailo Karuskevich, Vladimir Gliha, Tomaž Vuherer, 2013, original scientific article Abstract: An identification and quantitative analysis of the deformation relief of the aluminium alloy for an aircraft construction based on a digital-image processing has been performed. The behaviour of defects has been assessed on the basis of diagnostics results for individual stages of the deformation process. It has been established that the individual stages of the damage-accumulation process are characterised by the values of integral-image parameters. Based on the consecutive processing of the data on the surface cyclic deformation, the main regularities of the propagation of defects have been found. Theoretical preconditions have been substantiated and experimental results obtained.
Keywords: fatigue, surface, digital image, diagnostics, accumulated damage, defect propagation, evaluation
Published in DKUM: 10.07.2015; Views: 1175; Downloads: 97
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