Combined effect of both surface finish and sub‐surface porosity on component strength under repeated load conditions

McMillan, Alex; Jones, Rhys

doi:10.1002/eng2.12248

Cited by 7 publications

(5 citation statements)

References 106 publications

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“…The proof strain for the material is given by the term Fty/E; hence the function for e w defined by equation ( 8) can be regarded as being related to the effect of strain, or work, hardening at the root of the notch or thread root. Work by McMillan and Jones (2020) shows that plastic deformation at the notch remains highly localised, reference [7]. Hence, it is possible to conclude that the strain at the notch or the thread root of a bolt is controlled by the nett section of the notched component or the core of the thread.…”

Section: Effect Of Stress Concentration and Materials Properties On M...mentioning

confidence: 99%

“…An alternative and possibly more accurate way of estimating the material constant a 1 would be to use a value for the strain hardening factor e w based on the value of the more accurately known value of the material constant for unnotched 300M obtained using data sets 4 and 5. Hence, rearranging equation (7) to calculate the strain hardening factor for unnotched specimens, stress concentration K t = 1.0:…”

Section: Additional S-n Curves For 300m Carbon Steelmentioning

confidence: 99%

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An empirical approach to a comprehensive damage-equivalent stress function for fatigue

Welch¹

2022

FME Transactions

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This paper develops an empirical damage-equivalent stress function for fatigue. Classical analysis methods are used to 'fit' an equation to a number of S-N curves for various grades of carbon steel. The resulting equivalent-damage stress function is applicable to steels subjected to a wide range of heat treatments, from normalised up to hardened and tempered to 1900MPa. It is also applicable to a wide range of stress concentrations, unnotched up to Kt = 5.0 and typical of screw threads. A range of stress ratios and mean stresses are also considered. The function overcomes some of the limitations of existing methods of 'correcting' for mean stress. Existing methods are limited in that, while they may give good results over a range of conditions, there are some circumstances where the results are highly inaccurate. The damage-equivalent stress function is suitable for use in automated calculation procedures such as spreadsheets, MathCAD ©, and SMathStudio ©.

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Section: Effect Of Stress Concentration and Materials Properties On M...mentioning

confidence: 99%

Section: Additional S-n Curves For 300m Carbon Steelmentioning

confidence: 99%

An empirical approach to a comprehensive damage-equivalent stress function for fatigue

Welch¹

2022

FME Transactions

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“…Sa, Sq, Sv) and the internal porosity as well as the tensile strength (Zhu et al 2020). AM's rough surface texture, particularly surface notches, some of which are open surface pores, could lead to a shortened fatigue life (Nasab et al 2020, McMillan and Jones 2020, Du Plessis and Beretta 2020.…”

Section: Link Materials Ratio Curve With Am Open Surface Poresmentioning

confidence: 99%

Material ratio curve of 3D surface topography of additively manufactured parts: an attempt to characterise open surface pores

Lou

Zhu²,

Zeng

et al. 2021

Surf. Topogr.: Metrol. Prop.

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Surface topography of additively manufactured components often contains 3D features, e.g. particles, open surface pores. X-ray computed topography can capture these features, allowing measurement data to be used for 3D surface texture characterisation. On the basis of the newly developed 3D surface texture parameters, this paper investigates material ratio curves of the surfaces produced by additive manufacturing processes, i.e. selective laser melting and high speed sintering. The material ratio curves of these surfaces vary in their shapes, depending on the specific process and associated process parameters, as well as surface orientations. Re-entrant topography features can result in recess shapes on the material ratio curve at the surface heights where these features locate. This unique characteristic makes the material ratio curve an effective analysis tool to differentiate various AM surface topographies, allowing surface texture to be linked with process control and functional assessment. Furthermore, Vvv (valley void volume) is identified as a useful volume parameter to characterise the open surface pores of AM surfaces. The material ratio Mr2 for the determination of Vvv is discussed with the consideration of three options to address the open surface pores. The secant scanning approach proposed by ISO 13565-2 and the manual set ratio at the first sharp drop of the material ratio curve were found to be able to achieve reasonable results for the AM open surface pore characterisation.

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“…Generally the process of fatigue is characterised by test or empirical formulae derived from test data. In these studies [17,18,19], it is argued that fatigue must be a physical process, and as such should be possible to model directly.…”

Section: Model Of a Test Specimen With Imperfect Geometry Includedmentioning

confidence: 99%

Opportunities and prejudices in synthetic experiments

McMillan

2021

IOP Conf. Ser.: Mater. Sci. Eng.

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Synthetic experiments, meaning experiments performed using models of reality, are used in a variety of contexts. In recent years, advances in computing capability have led to the development of modelling capability that replicates reality to such an extent that in some circumstances it is difficult to distinguish the model from reality. From a science or engineering perspective, computational analysis models are used to replicate or predict phenomena such as fluid flow or stress in a machine component, but the capability has also crossed over into the arts enabling the computer generated imagery (CGI) used in films, and the augmented reality (AR) of video games. This paper reviews the application of synthetic experiments to replace physical experiments and discusses some of the advantages and pitfalls of such an approach in the context of education. The trend for democratizing analysis is considered, and the dangers of misinterpreting results are discussed. A discussion of the issue of model over-simplification is given, and finally the use of synthetic experiments as part of a systematic scientific investigation is also considered.

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Combined effect of both surface finish and sub‐surface porosity on component strength under repeated load conditions

Cited by 7 publications

References 106 publications

An empirical approach to a comprehensive damage-equivalent stress function for fatigue

An empirical approach to a comprehensive damage-equivalent stress function for fatigue

Material ratio curve of 3D surface topography of additively manufactured parts: an attempt to characterise open surface pores

Opportunities and prejudices in synthetic experiments

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