The correlation of fractal dimension to fracture surface slope for fatigue crack initiation analysis under bending-torsion loading in high-strength steels

Macek, Wojciech; Branco, R.; Podulka, Przemysław; Nejad, Reza Masoudi; Costa, J.D.; Ferreira, José Pedro; Capela, C.

doi:10.1016/j.measurement.2023.113169

Cited by 15 publications

(2 citation statements)

References 49 publications

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“…The surfaces of selected fatigue fractures were subjected to topography analysis in order to determine differences in fatigue mechanisms for the considered variants. Surface examination was made in the ROI using volume parameters Vx and height parameters Sx, as specified in the ISO 25178-2 standard [30]. As part of the analysis, two parameters were used: an arithmetic mean height Sa and a void volume Vv.…”

Section: Methodsmentioning

confidence: 99%

Fracture Surface Topography Parameters for S235JR Steel Adhesive Joints After Fatigue Shear Testing

Kubit,

Macek,

Zielecki

et al. 2023

Adv. Sci. Technol. Res. J.

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This paper presents the experimental results of a study investigating the effect of holes and notches made on the overlap ends on the strength of adhesive joints. Single-lap joints made of S235JR steel sheets bonded with Araldite 2024-2 epoxy adhesive were tested. For comparative reasons, static shear strength tests and high-cycle fatigue strength tests were performed. Adhesive-filled joints having three holes, each with a diameter of 3 mm, and notches, each 3 mm wide and 4 mm long, were tested and compared with reference joints, i.e. without modification. The assumption was to determine whether the structural modifications would reduce the peak peel and shear stresses that are typical of this type of joints. Results of the static strength tests showed no significant effect of the applied modifications on the strength of the joints. However, in terms of fatigue strength, the results demonstrated a significant improvement in fatigue life, the value of which increased in the low-cycle fatigue region by 328.6% for the joint with notches and by 640.8% for the joint with holes. A smaller yet still positive effect of the applied modifications was shown for high-cycle fatigue. For a variable load with the maximum value of 9 MPa, the fatigue life increased by 215.9% for the variant with notches and by 183.3% for the variant with holes. Surface topography of fatigue fractures was examined by determining roughness parameters on the overlap ends in the samples. Significant differences were shown, with the selected roughness parameters being significantly lower for the reference variant than for the variants with notches and holes. It was shown that the applied structural modifications led to increasing the fatigue strength to 8.5 MPa for the limit number of cycles equal to 2•106, when compared to the reference variant for which the fatigue strength was 8 MPa.

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Section: Methodsmentioning

confidence: 99%

Fracture Surface Topography Parameters for S235JR Steel Adhesive Joints After Fatigue Shear Testing

Kubit,

Macek,

Zielecki

et al. 2023

Adv. Sci. Technol. Res. J.

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“…It is a mathematical statistical theory to study the self-similarity of objects, and it is a relatively accurate quantitative representation reflecting the inhomogeneity of the basic properties of a formation in three-dimensional space [6,7]. After decades of exploration and research, the fractal dimension has become relatively mature in the fields of physics [8], mathematics [9], geology [10,11] and materials [12] and has achieved corresponding results. In the field of geology, it is mainly used in coal seams [13,14], tight sandstone reservoirs [15], mud shale [16,17] and other pore structure characterization [18,19]; reservoir heterogeneity characterization [20]; and determining the influencing factors of reservoir densification [21].…”

Section: Introductionmentioning

confidence: 99%

Research on Fractal Characteristics and Influencing Factors of Pore-Throats in Tight Sandstone Reservoirs: A Case Study of Chang 6 of the Upper Triassic Yanchang Formation in Huaqing Area, Ordos Basin, China

Nan,

Lin,

Lai

et al. 2023

Minerals

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In recent years, tight sandstone oil and gas have been an important area for unconventional oil and gas exploration and development in China. It is of great significance to clarify the pore-throat structure characteristics of tight sandstone reservoirs to guide production practices. This study takes the tight sandstone of the sixth member of the Yanchang Formation in the Huaqing area, Ordos Basin, as an example, based on experimental methods such as high-pressure mercury intrusion, cast thin sections and scanning electron microscopy. At the same time, the pore-throat structure of tight sandstone reservoirs is divided into three types using the tube-bundle and spherical fractal models. The corresponding pore and throat radius distribution, pore-throat combination mode and influencing factors of various pore-throats are studied. The results show that the fractal dimension of type I pore-throats is the smallest, and the distribution of their pore-throat radii is the most uniform. They are dominated by intercrystalline pores and dissolution pores with tube-bundle throats and small pores with small throats. Type II pore-throats have the largest fractal dimension and the worst pore-throat uniformity. They are dominated by residual primary intergranular pores with necked throats and large pores with small throats. The type III pore-throat fractal dimension is in the middle, mainly composed of residual dissolved intergranular pores with pore-reduced throats, sheet-like and curved sheet-like throats, and large pores with large throats. The influence of different pore-throat combinations on the reservoir is reflected in the different characteristics of mercury injection parameters. The main influencing factors for the differences in the fractal dimensions of different pore-throats are diagenesis, rock composition and pore-throat combination type. Diagenesis and rock composition, in turn, affect the type and development degree of pore-throats, as well as the combination of pore-throats. The purpose of this study was to clarify the internal connection modes of different homogeneous pore-throats and their influencing factors, enrich the theoretical basis for the study of tight sandstone reservoirs and provide theoretical guidance for their exploration and development.

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Exploring the impact of phase-shifted loading conditions on fatigue life of S355J2 mild steel with different machine learning approaches

Owsiński,

Gupta,

Lachowicz

et al. 2024

Int J Adv Manuf Technol

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The correlation of fractal dimension to fracture surface slope for fatigue crack initiation analysis under bending-torsion loading in high-strength steels

Cited by 15 publications

References 49 publications

Fracture Surface Topography Parameters for S235JR Steel Adhesive Joints After Fatigue Shear Testing

Fracture Surface Topography Parameters for S235JR Steel Adhesive Joints After Fatigue Shear Testing

Research on Fractal Characteristics and Influencing Factors of Pore-Throats in Tight Sandstone Reservoirs: A Case Study of Chang 6 of the Upper Triassic Yanchang Formation in Huaqing Area, Ordos Basin, China

Exploring the impact of phase-shifted loading conditions on fatigue life of S355J2 mild steel with different machine learning approaches

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