Fatigue strength study based on geometric shape of bulk defects in cast steel

Horvath, Michael; Stoschka, Michael; Fladischer, Stefan

doi:10.1016/j.ijfatigue.2022.107082

Cited by 8 publications

(5 citation statements)

References 25 publications

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“…Six specimens were tested utilizing a stress ratio of R = 0.5 and stress ranges between 100 MPa and 175 MPa at a testing frequency of approximately 75 Hz. The test strategy introduced in preceding studies [10,11,17] was followed for the experimental investigations. This strategy involved testing of each individual specimen at up to two target load levels.…”

Section: High-cycle Fatigue Investigations Of Bulk Defect-afflicted S...mentioning

confidence: 99%

“…Each part X i follows a differential equation [98] which can be integrated to give Equation (11) for the uniaxial load case [28,30].…”

Section: Parametrization Of Elastic-plastic Materials Modelmentioning

confidence: 99%

“…However, despite the latest advances in numerical simulations in the casting process [4][5][6][7][8], the formation of manufacturing processbased shrinkage imperfections within highly loaded sections cannot be fully prevented. Due to high-volume contraction, these spatial defect structures often reach dimensions of several millimetres [9][10][11][12]. Hence, the fatigue strength of the respective components is significantly affected by the presence of such macroscopic imperfections [13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

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A Numerically Efficient Method to Assess the Elastic–Plastic Strain Energy Density of Notched and Imperfective Cast Steel Components

2023

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The fatigue strength of cast steel components is severely affected by manufacturing process-based bulk and surface imperfections. As these defect structures possess an arbitrary spatial shape, the utilization of local assessment methods is encouraged to design for service strength. This work applies the elastic–plastic strain energy density concept to study the fatigue strength properties of a high-strength cast steel alloy G12MnMo7-4+QT. A fatigue design limit curve is derived based on non-linear finite element analyses which merges experimental high-cycle fatigue results of unnotched and notched small-scale specimens tested at three different stress ratios into a unique narrow scatter band characterized by a scatter index of 1:TΔW¯(t)=2.43. A comparison to the linear–elastic assessment conducted in a preceding study reveals a significant improvement in prediction accuracy which is assigned to the consideration of the elastic–plastic material behaviour. In order to reduce computational effort, a novel approximation is presented which facilitates the calculation of the elastic–plastic strain energy density based on linear–elastic finite element results and Neuber’s concept. Validation of the assessment framework reveals a satisfying agreement to non-linear simulation results, showing an average root mean square deviation of only approximately eight percent in terms of total strain energy density. In order to study the effect of bulk and surface imperfections on the fatigue strength of cast steel components, defect-afflicted large-scale specimens are assessed by the presented elastic–plastic framework, yielding fatigue strength results which merge into the scatter band of the derived design limit curve. As the conducted fatigue assessment is based solely on linear–elastic two-dimensional simulations, the computational effort is substantially decreased. Within the present study, a reduction of approximately 400 times in computation time is observed. Hence, the established assessment framework presents an engineering-feasible method to evaluate the fatigue life of imperfective cast steel components based on rapid total strain energy density calculations.

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Section: High-cycle Fatigue Investigations Of Bulk Defect-afflicted S...mentioning

confidence: 99%

“…Each part X i follows a differential equation [98] which can be integrated to give Equation (11) for the uniaxial load case [28,30].…”

Section: Parametrization Of Elastic-plastic Materials Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Numerically Efficient Method to Assess the Elastic–Plastic Strain Energy Density of Notched and Imperfective Cast Steel Components

2023

Self Cite

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“…Such cases include pressure and temperature rise, working environment, material characteristics, element thickness, quantity, dimensions, arrangement of defects, etc. Of particular interest in terms of strength assessment are defects of "mechanical origin" such as scratches and risks [1][2][3][4][5]. Since any device undergoes repair or reconstruction during its service life, mechanical damage from the locksmith tool and other repair devices remains inevitably in the repair places and surfaces adjacent to these places.…”

Section: Introductionmentioning

confidence: 99%

Strength analysis of flat manhole cover in case of change of location and inclination angle of two mutually intersecting scratches

Rubtsov,

Kulakov,

Gracheva

et al. 2023

J. Phys.: Conf. Ser.

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Mechanical damages of the main structural elements of the process equipment of hazardous production facilities are quite often detected during the revision process after repairs when assessing the quality of the work performed. One of the most common mechanical damages on the surface of parts and assemblies of technical devices includes scratches and risks. Significant scratches and risks that have a relatively large area and depth and limit the commissioning of the facility are subject to sampling and removal during re-repair. Superficial and non-extended scratches and risks do not belong to unacceptable defects, the technical device should not be taken into account, and further operation occurs with their presence. During further operation of the facility, such defects may not manifest themselves in any way, but may be high-voltage concentrators, which in the vast majority of cases are not critical. However, the presence of two or more scratches on the surface of the structural elements, their different location relative to each other, and therefore different mutual influence, can have a significant effect on the redistribution of zones and values of increased stresses on the surfaces where they are located. In the current regulatory and technical documents for diagnostics, these points are not considered, and accordingly are not taken into account. Therefore, the actual work is to perform a strength analysis of a flat manhole cover with two scratches, which have a different location on the surface, and a different angle of intersection relative to each other.

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“…Currently, research on the stability and bearing capacity of steel frame materials with defects mostly focuses on large and complex structures, such as mesh frames and mesh shell structures. The defects studied are primarily initial geometrical defects and residual stresses in the structure or members [ 9 , 10 , 11 , 12 , 13 ]. Usually, the initial geometric defects mainly refer to the buckling of the bar, increasing the perturbation and deformation of the material, and the defects’ shape can be simulated by sinusoidal waves [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

Investigation on Buckling Performance of Prefabricated Light Steel Frame Materials under the Action of Random Defects during Construction

Yao,

Chen,

Yang

et al. 2023

Materials

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This investigation proposes an analytical approach for analyzing the impact of random defects on light steel frame materials. The addition of random defects for the overall and the component units was achieved by integrating Matlab R2022a and Ansys R19.0 finite element software. Nonlinear analysis was conducted to calculate ultimate load factors and nodal ultimate displacements of the materials under various random defects at each stage of construction. A two-factor analysis was employed to investigate the effects of random defects on the calculation results during different construction stages. The investigation reveals that the response of the light steel frame materials to initial defects is more pronounced during the construction stage. Moreover, the construction stage is the main factor that affects the ultimate load factor and nodal ultimate displacement, compared with random defects. The influence of different random defects on structural displacements varies significantly. The displacement development of the light steel frame materials under the influence of component unit defects tends to be more rapid than that of the overall defects. However, their buckling critical loads are essentially similar.

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Fatigue strength study based on geometric shape of bulk defects in cast steel

Cited by 8 publications

References 25 publications

A Numerically Efficient Method to Assess the Elastic–Plastic Strain Energy Density of Notched and Imperfective Cast Steel Components

A Numerically Efficient Method to Assess the Elastic–Plastic Strain Energy Density of Notched and Imperfective Cast Steel Components

Strength analysis of flat manhole cover in case of change of location and inclination angle of two mutually intersecting scratches

Investigation on Buckling Performance of Prefabricated Light Steel Frame Materials under the Action of Random Defects during Construction

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