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Intermediate strain rate testing methodologies and full-field optical strain measurement techniques for composite materials characterisation

Intermediate strain rate testing methodologies and full-field optical strain measurement techniques for composite materials characterisation
Intermediate strain rate testing methodologies and full-field optical strain measurement techniques for composite materials characterisation
Two optical full-field strain measurement techniques, Digital Image Correlation and the Grid Method, are applied to characterise the strain-rate dependent constitutive behaviour of composite materials. Optical strain measurement techniques based on full-field images are well established for material characterisation in the quasi-static strain rate region, however in this work they are developed to study the material behaviour at intermediate strain rates, which is relatively unexplored. For this purpose a testing methodology that combines high speed imaging and the use of a high speed test machine is devised. The overall goal is to extract composite materials constitutive parameters to be used in the modelling of strain rate dependent behaviour. Particularly the strain rate dependence of the stiffness of glass and carbon fibre reinforced epoxy materials is investigated. A characterisation procedure based on off-axis specimens with oblique end-tabs is developed and applied to the study of the shear behaviour of a carbon/epoxy composite material.

The research in the PhD programme constitutes an essential first step for more profitable applications of full-field measurement techniques to high speed testing. Full-field data acquired with the experimental methodology devised here can be used to investigate non linear material behaviours. Furthermore this experimental methodology, applied to specimens that generate non uniform strain fields, can produce strain maps useful for the application of the Virtual Fields Method. This will lead to a reduction of the experiments needed to characterise materials.
Longana, M.L.
155c3f93-d37e-4744-ba96-3cbb9a575e83
Longana, M.L.
155c3f93-d37e-4744-ba96-3cbb9a575e83
Barton, Janice
9e35bebb-2185-4d16-a1bc-bb8f20e06632

Longana, M.L. (2014) Intermediate strain rate testing methodologies and full-field optical strain measurement techniques for composite materials characterisation. University of Southampton, Engineering and the Environment, Doctoral Thesis, 209pp.

Record type: Thesis (Doctoral)

Abstract

Two optical full-field strain measurement techniques, Digital Image Correlation and the Grid Method, are applied to characterise the strain-rate dependent constitutive behaviour of composite materials. Optical strain measurement techniques based on full-field images are well established for material characterisation in the quasi-static strain rate region, however in this work they are developed to study the material behaviour at intermediate strain rates, which is relatively unexplored. For this purpose a testing methodology that combines high speed imaging and the use of a high speed test machine is devised. The overall goal is to extract composite materials constitutive parameters to be used in the modelling of strain rate dependent behaviour. Particularly the strain rate dependence of the stiffness of glass and carbon fibre reinforced epoxy materials is investigated. A characterisation procedure based on off-axis specimens with oblique end-tabs is developed and applied to the study of the shear behaviour of a carbon/epoxy composite material.

The research in the PhD programme constitutes an essential first step for more profitable applications of full-field measurement techniques to high speed testing. Full-field data acquired with the experimental methodology devised here can be used to investigate non linear material behaviours. Furthermore this experimental methodology, applied to specimens that generate non uniform strain fields, can produce strain maps useful for the application of the Virtual Fields Method. This will lead to a reduction of the experiments needed to characterise materials.

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More information

Published date: March 2014
Organisations: University of Southampton, Civil Maritime & Env. Eng & Sci Unit

Identifiers

Local EPrints ID: 366539
URI: http://eprints.soton.ac.uk/id/eprint/366539
PURE UUID: 543d2557-5dc8-4780-a2a2-823b676a3dbc

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Date deposited: 15 Oct 2014 12:56
Last modified: 18 Jul 2017 02:10

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Contributors

Author: M.L. Longana
Thesis advisor: Janice Barton

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