Turnbull, A; Crocker, L E (2014) Four point bend testing - finite element analysis of the stress and strain distribution. NPL Report. MAT 63

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Abstract

Finite element computations of the stress and strain distribution on the tensile surface of a four point bend specimen of a 13Cr stainless steel (SS) were carried out in order to resolve the query of the method most appropriate for setting the total strain to achieve 0.2% plastic strain; in particular, whether to use tensile or bend data. Computations were carried out with very low friction at the rollers and subsequently with varying degrees of friction. The recommendation is that the four point bend specimen should be loaded to a longitudinal strain corresponding to the total strain to achieve 0.2% plastic strain as determined in separate uniaxial tensile testing. The force required to achieve that strain can be affected by friction at the rollers but provided the specimen is strain gauged this will have no impact on the strain in the central section of the specimen. However, friction at the inner rollers can induce an elevated stress on the tensile surface of the specimen opposite and this may cause cracking at that location. Such cracking should be considered an artefact.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	MAT 63
Keywords:	four point bend, finite element
Subjects:	Advanced Materials Advanced Materials > Corrosion
Last Modified:	02 Feb 2018 13:13
URI:	http://eprintspublications.npl.co.uk/id/eprint/6097

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