Obtaining a lower estimate of the fatigue limit of metals by a simplified quantitative thermometric approach in a low-cost one-specimen test

Schaefer, Florian; Rosar, Jan; Wu, Haoran; Starke, Peter; Marx, Michael

doi:10.1016/j.ijfatigue.2022.106729

Cited by 5 publications

(12 citation statements)

References 18 publications

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“…More experimental results, from different material and other stress ratios than R = −1, as well as more details on the test setup can be found in Schaefer et al. (2022a).…”

Section: Experimental Methods and Resultsmentioning

confidence: 99%

“…First, a concise overview of the fundamental thermodynamic equations and their simplifications for practicable application is given, followed by an explanation of the NTC-QT methodology in comparison to the IR-QT methodology using a short recap of our previous work on the topic, already published in more detail by Schaefer et al. (2022a, b).…”

Section: Context and Motivationmentioning

confidence: 99%

“…The deformation processes in the fatigue strength regime that eventually lead to damage, i.e. to crack initiation, dissipate energy and thus impact the heat generation within the specimen (Staerk, 1980, 1982a; Schaefer et al. , 2022a).…”

Section: Context and Motivationmentioning

confidence: 99%

“…Hence, 3 questions arise:Does the test results really benefit from a more elaborated test setup such as clamping thermostats or excessive thermal isolation as mentioned and used by many authors?How stable is the evaluation with both methods under asymmetric thermal boundary conditions due to the experimental setup?Is a simple parabolic fit, were 3 sample points of the temperature profile suffice, as proposed by Staerk (1982a) as suitable as a more complex double-exponential fit derived from a one-dimensional heat equation that needs more or less continuous temperature profile data (Guo et al. , 2015; Schaefer et al. , 2022a) regarding the two questions above?…”

Section: Context and Motivationmentioning

confidence: 99%

“…(3) Is a simple parabolic fit, were 3 sample points of the temperature profile suffice, as proposed by Staerk (1982a) as suitable as a more complex double-exponential fit derived from a one-dimensional heat equation that needs more or less continuous IJSI 14,1 temperature profile data (Guo et al, 2015;Schaefer et al, 2022a) regarding the two questions above?…”

Section: Context and Motivationmentioning

confidence: 99%

See 4 more Smart Citations

Quantitative thermography: a powerful but simple tool to assess the fatigue strength of metals in a one-specimen test–capabilities and limitations in the test setup

Rauber

Motz²,

Schaefer³

2022

IJSI

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PurposeThe aim of the study is the question, that is, which evaluation method for the measured temperature profile is more suitable and feasible for quantitative thermometry (QT): A simple measurement setup based on 3-point temperature sensing by means of semiconductor sensors (NTCs) or thermographic methods which offer 2-dimensional (2D) temperature measurements of the sample with good spatial resolution but an inferior temperature sensitivity. What experimental effort is required to adjust the test setup to satisfy the boundary conditions of the underlying thermodynamic equations?Design/methodology/approachIn this paper results of both methods are contrasted and the error of QT measurement is assessed by finite element analysis (FEA) in this follow-up.FindingsThe low-cost NTC method allows a straightforward determination of a lower estimate of the fatigue strength with only a very small measurement error. Even asymmetries in the thermal boundary conditions of the test setup are broadly tolerated, as well as a lack of thermal isolation.Practical implicationsThe method is restricted to metallic materials without phase transitions during fatigue in the fatigue strength regime.Originality/valueQT is not a new method. The assessment of the methods proposed in the literature regarding their practicability in terms of accuracy is innovative focus of this work. Nevertheless, highly accurate thermometric measurements can be performed by using simple commercial sensors in combination with a standard digital multimeter.

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“…More experimental results, from different material and other stress ratios than R = −1, as well as more details on the test setup can be found in Schaefer et al. (2022a).…”

Section: Experimental Methods and Resultsmentioning

confidence: 99%

Section: Context and Motivationmentioning

confidence: 99%