Development and Qualification of an Algorithm for the Determination of the Initial Linear Portion of a Force Versus Displacement Record

Scibetta, M.; Schuurmans, J.

doi:10.1520/jte12618

Cited by 11 publications

(4 citation statements)

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“…In 2013, ASTM Task Group E08.07.05 on Ductile Fracture Toughness undertook an activity aimed at developing a set of standard data sets to help users validate their analysis programs. Within this analytical round-robin, eight data sets were distributed to participants, developed using 1TC(T) and 1/2TC(T) 7 compact specimens, and 1TSE(B) single-edge bend specimens of an aluminum alloy and three steels [10].…”

Section: Discussionmentioning

confidence: 99%

“…Several authors have proposed algorithms for determining the linear range in a test record [5][6]. In 2004, Scibetta and Schuurmans [7] addressed the question regarding how to determine the number of points to be used in the linear fit, below a knee where slope shows a significant decrease. In their algorithm, an iterative process of successive linear regressions on varying window sizes is used to search for the window that corresponds to the lowest normalized residual.…”

Section: Introductionmentioning

confidence: 99%

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Use and validation of the slope determination by the analysis of residuals (SDAR) algorithm

Lucon¹

2019

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The Slope Determination by the Analysis of Residuals (SDAR) algorithm has recently been standardized in ASTM E3076-18 for the determination of the slope in the linear region of a test record. It offers an automated and objective linear-fitting method, based on the least normalized residual, and in its full form provides metrics for evaluating the quality of the test record and of the resultant fit. In this investigation, SDAR was used to calculate values of crack size in elastic-plastic fracture toughness tests, conducted in accordance with ASTM E1820-18 by means of the single-specimen elastic compliance methodology. Our analyses show that the use of SDAR is not advisable in case of noisy unloading/reloading cycles and/or in the presence of significant hysteresis, since the most linear portion identified by the algorithm may not necessarily represent the true elastic behavior of the specimen. Such issues could be alleviated by increasing the minimum number of data points used from 20 % of the search range (E3076) to at least 50 %. Nevertheless, SDAR remains an extremely useful tool to determine a repeatable and operator-independent slope in numerous types of mechanical tests, such as tensile tests, linear elastic fracture mechanics tests, and others.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Use and validation of the slope determination by the analysis of residuals (SDAR) algorithm

Lucon¹

2019

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“…To reduce the variability due to the interpretation of the individual laboratory, and to put each modulus measurement on a consistent basis, we reanalyzed each stressstrain curve to estimate the elastic modulus using a technique [33] based on the method of Scibetta and Schuurmans [34]. These reanalyzed moduli are denoted by the symbol E GA , to differentiate them from the moduli that the participants calculated and reported, denoted by E. In addition to estimating the modulus, the method includes some checks on the quality of the data that may be useful for laboratories that seek to improve their modulus measurement.…”

Section: Elastic Modulusmentioning

confidence: 99%

“…4 Use the Scibetta-Schuurmans [34] algorithm to determine optimum fit window and calculate the slope, which is the elastic modulus E GA , in normalized form. The Scibetta-Schuurmans algorithm finds the optimal region for determining the modu lus by performing a linear regression of stress on strain on every possible subset of data in the region e o < e < e t that contains at least 20 % of the data.…”

Section: Almentioning

confidence: 99%

Repeatability and reproducibility of compression strength measurements conducted according to ASTM E9

Luecke

Ma²,

Graham

et al. 2009

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Ten commercial laboratories participated in an interlaboratory study to estab lish the repeatability and reproducibility of compression strength tests conducted according to ASTM International Standard Test Method E9. The test employed a cylindrical aluminum AA2024-T351 test specimen. Participants measured elastic modulus and 0.2 % offset yield strength, YS(0.2 % offset), using an extensometer attached to the specimen. The repeatability and reproducibility of the yield strength measurement, expressed as coefficient of variations were cv r = 0.011 and cv R = 0.020 The reproducibility of the test across the laboratories was among the best that has been reported for uniaxial tests. The reported data indicated that using diametrally opposed extensometers, instead of a single extensometer, doubled the precision of the test method. Laboratories that did not lubricate the ends of the specimen mea sured yield stresses and elastic moduli that were smaller than those measured in laboratories that lubricated the specimen ends. A finite element analysis of the test specimen deformation for frictionless and perfect friction could not explain the dis crepancy, however. The modulus measured from stress-strain data were reanalyzed using a technique that finds the optimal fit range, and applies several quality checks to the data. The error in modulus measurements from stress-strain curves generally increased as the fit range decreased to less than 40 % of the stress range.

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Review of and a new approach to elastic modulus evaluation for fatigue design of metallic components

Maciolek

Wagener

Melz

2021

International Journal of Fatigue

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Development and Qualification of an Algorithm for the Determination of the Initial Linear Portion of a Force Versus Displacement Record

Cited by 11 publications

References 1 publication

Use and validation of the slope determination by the analysis of residuals (SDAR) algorithm

Use and validation of the slope determination by the analysis of residuals (SDAR) algorithm

Repeatability and reproducibility of compression strength measurements conducted according to ASTM E9

Review of and a new approach to elastic modulus evaluation for fatigue design of metallic components

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