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Elastic modulus measurement.

Lord, J D; Morrell, R (2007) Elastic modulus measurement. Measurement Good Practice Guide. 98

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Elastic modulus is an intrinsic material property and a key parameter in engineering design and materials development. A wide range of test methods is available for measuring modulus, but there is currently some uncertainty within parts of the user community about the reliability of modulus data, to the extent that many use standard handbook values in their calculations and designs. This is not recommended and can be addressed through good experimental practice and careful measurement.
Both static and dynamic modulus methods are covered in this Guide, presented in separate sections with details on the different test methods and on practical issues affecting the quality and accuracy of the measurement. The Good Practice Guide draws together some of the background to the techniques, discusses the current standards, and highlights a number of key factors crucial to obtaining good quality measurement. Examples are given where appropriate to highlight aspects of the test methodology, based both on measurements made at NPL and from a number of intercomparison exercises.
Practical issues relevant to the current test methods are discussed, including test-piece preparation, alignment, strain measurement, data analysis methods, uncertainty budgets and the use of reference materials, together with a range of examples, and recommendations for obtaining good quality modulus data.
Results presented show that it is possible to obtain good modulus data from the tensile test, but this generally requires a separate and dedicated test set-up using high quality averaging strain measurement and data analysis procedures, focusing only on the early part of the stress-strain curve. Dynamic methods are generally more versatile, and can be more readily applied to high temperature measurement and to brittle materials with good accuracy.
In both cases, following the procedures recommended, accurate values of modulus can be realised, with typical uncertainties in the measured values as low as 1-2%

Item Type: Report/Guide (Measurement Good Practice Guide)
Subjects: Advanced Materials
Advanced Materials > Mechanical Measurement
Last Modified: 02 Feb 2018 13:15
URI: http://eprintspublications.npl.co.uk/id/eprint/3782

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