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The development of a novel technique for small ring specimen tensile testing

Kazakeviciute, J.; Rouse, J.P.; De Focatiis, D.S.A.; Hyde, C.J.

Authors

J. Kazakeviciute

JAMES ROUSE James.Rouse@nottingham.ac.uk
Nottingham Research Fellow

Abstract

The wide scale use of small specimens in routine testing programs could significantly reduce material resource requirements (factors of 10 are easily achievable). This is a major benefit to situations where there is not enough material to manufacture conventional, full-size specimens, such as first-stage gas turbine blade roots. However, limitations exist due to concerns over size effects, manufacturing difficulties, uncertainties related to the application of representative loading conditions and complex interpretation procedures of non-standard data. Due to these limitations, small specimen testing techniques have been mostly applied in ranking exercises and to determine approximate or simple material parameters such as Young’s modulus, minimum creep strain rate and fracture toughness. The small ring method is a novel, high sensitivity small specimen technique for creep testing that has been extended in the present work to the determination of tensile material properties. The main advantages of the small ring specimen are that it is self-aligning and has a large equivalent gauge length in comparison to other small specimens, resulting in much higher testing sensitivity. In the present work, this specimen type mimics conventional, full-size, monotonic testing, allowing for observations of elastic and plastic material response to be made. Wrought aluminium alloy 7175-T7153 small rings were tested at room temperature at 5 different loading (displacement) rates and the results compared to conventional, full-size, monotonic specimen equivalents. Finite element analysis was conducted in order to evaluate the equivalent gauge section and equivalent gauge length in the small ring specimen (which varied between circa 0.35–1.4 mm2 and 25–45 mm, respectively) to facilitate these comparisons. An analytical solution has also been derived in order to validate the finite element analysis.

Journal Article Type Article
Publication Date Feb 1, 2019
Journal Theoretical and Applied Fracture Mechanics
Print ISSN 0167-8442
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 99
Pages 131-139
DOI https://doi.org/10.1016/j.tafmec.2018.11.016
Keywords Small ring specimen; Tensile testing; Finite element analysis; Material properties; Aluminium
Publisher URL https://www.sciencedirect.com/science/article/pii/S0167844218305214?via%3Dihub
Additional Information This article is maintained by: Elsevier; Article Title: The development of a novel technique for small ring specimen tensile testing; Journal Title: Theoretical and Applied Fracture Mechanics; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.tafmec.2018.11.016; Content Type: article; Copyright: © 2018 Elsevier Ltd. All rights reserved.

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