Influence of Friction on the Response of Small Punch Test

Prakash, Raghu V.; Arunkumar, S.

doi:10.1007/s12666-015-0769-4

Cited by 16 publications

(4 citation statements)

References 15 publications

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“…As the 𝜇 increases, not only the peak value of 𝜀 𝑝 is found to be much higher but also its localisation in the material gradually moves away from the punch pole. A similar conclusion was made by other authors, who also observed that lubrication in experimental conditions reduces the ultimate load and moves the failure site closer to the pole of the punch [32].…”

Section: Fig 9 Equivalent Plastic Strain At the Punch-specimen Polesupporting

confidence: 89%

Experimental and Numerical Small Punch Tests of the 14Cr ODS Ferritic Steel

Nowik

Oksiuta

2022

Acta Mechanica Et Automatica

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Nowadays, various small specimen test techniques have gained wide popularity and appreciation among researchers as they offer undoubtful benefits in terms of structural material characterisation. This paper focuses on small punch tests (SPTs) performed on small-sized disc specimens to assess the mechanical properties of 14Cr oxide dispersion strengthened (ODS) steel. A numerical model was established to support experimental data and gain deeper insight into complex strain states developing in a deformed specimen. Modern evaluation procedures were discussed for obtaining mechanical properties from the small punch force-deflection response and were compared with the literature. Applicability and universality of those relations at different test conditions were also studied. It appeared that different ball diameters used had negligible influence on yield point but strongly affected ultimate strength estimation. It was found that friction belongs to decisive factors determining strain distribution in samples, as dry conditions increase the peak strain and move its location farther from the punch pole.

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Section: Fig 9 Equivalent Plastic Strain At the Punch-specimen Polesupporting

confidence: 89%

Experimental and Numerical Small Punch Tests of the 14Cr ODS Ferritic Steel

Nowik

Oksiuta

2022

Acta Mechanica Et Automatica

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“…Another investigation confirmed the effect of friction on small punch results and investigated the effect of friction on automated ball indentation test results. 62 One study found that surface finish does not have a significant effect on the results experimentally, which appears to disagree with other studies, which state that surface roughness and the coefficient of friction have a significant effect. The results of this study are likely material specific and are only valid for the range of surface roughness investigated.…”

Section: Small Punch Specimensmentioning

confidence: 83%

Small specimen techniques for estimation of tensile, fatigue, fracture and crack propagation material model parameters

Kazakeviciute

Rouse

Focatiis

et al. 2021

The Journal of Strain Analysis for Engineering Design

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Small specimen mechanical testing is an exciting and rapidly developing field in which fundamental deformation behaviours can be observed from experiments performed on comparatively small amounts of material. These methods are particularly useful when there is limited source material to facilitate a sufficient number of standard specimen tests, if any at all. Such situations include the development of new materials or when performing routine maintenance/inspection studies of in-service components, requiring that material conditions are updated with service exposure. The potentially more challenging loading conditions and complex stress states experienced by small specimens, in comparison with standard specimen geometries, has led to a tendency for these methods to be used in ranking studies rather than for fundamental material parameter determination. Classifying a specimen as ‘small’ can be subjective, and in the present work the focus is to review testing methods that utilise specimens with characteristic dimensions of less than 50 mm. By doing this, observations made here will be relevant to industrial service monitoring problems, wherein small samples of material are extracted and tested from operational components in such a way that structural integrity is not compromised. Whilst recently the majority of small specimen test techniques development have focused on the determination of creep behaviour/properties as well as sub-size tensile testing, attention is given here to small specimen testing methods for determining specific tensile, fatigue, fracture and crack growth properties. These areas are currently underrepresented in published reviews. The suitability of specimens and methods is discussed here, along with associated advantages and disadvantages.

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“…With our current test rig, it was not possible to measure the thickness reduction of the specimen centre accurately. Having this measurement, it would be possible to estimate the friction coefficient which has a huge impact on the results and therefore on the identified parameters [6, 18, 19]. The friction coefficient was assumed with

\mu =0.2

, which is often used in literature [6, 20].…”

Section: Cd‐spt‐simulations – Calibration and Discussionmentioning

confidence: 99%

Identification of creep parameters from multi‐step relaxation tests on miniaturised specimen

Schirmer,

Selent,

Abendroth

et al. 2023

Proc Appl Math and Mech

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The small punch test (SPT) is a miniaturised method for thermo‐mechanical materials testing. The combination of simple specimen geometry and low required specimen volume is ideal for minimally invasive characterisation and monitoring of the current material condition in technological systems, including nuclear plants.The aim of the present study is to identify creep material properties of the chromium steel P91 (X10CrMoVNb9‐1) via small punch testing. It is examined to which extent a single relaxation test is suitable to replace several creep tests at different force levels. The inverse parameter identification method utilises a non‐linear optimisation approach in order to match the results of simulation and experiment. The simulation is performed using finite element analysis (FEA) and the considered material law aims to represent the high‐temperature behaviour of steels. To this end, a modified Liu–Murakami model is specifically used along with linear elasticity and non‐linear isotropic plasticity. We propose a strategy, that can be used to separately identify the Norton‐parameters from multi‐step relaxation tests performed on one specimen. Thereby, the applied strain (displacement, if utilising SPT) is kept constant after initial loading, which enables stress relaxation within the specimen. In case of the SPT, this behaviour yields a decreasing reaction force which approximately approaches a constant value. During the repeated loading phases, specimen failure may occur, due to further plastification of the specimen. Loading and relaxation cycles are repeated until specimen failure.The identified parameters are validated via small punch creep experiments at different force levels. It will be shown that good agreement is observed when comparing the sets of identified parameters.

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Influence of Friction on the Response of Small Punch Test

Cited by 16 publications

References 15 publications

Experimental and Numerical Small Punch Tests of the 14Cr ODS Ferritic Steel

Experimental and Numerical Small Punch Tests of the 14Cr ODS Ferritic Steel

Small specimen techniques for estimation of tensile, fatigue, fracture and crack propagation material model parameters

Identification of creep parameters from multi‐step relaxation tests on miniaturised specimen

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