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Determination of large deformation and fracture behaviour of starch gels from conventional and wire cutting experiments
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Document Title
Determination of large deformation and fracture behaviour of starch gels from conventional and wire cutting experiments
Author
Gamonpilas C, Charalambides MN, Williams JG
Name from Authors Collection
Affiliations
National Science & Technology Development Agency - Thailand; National Metal & Materials Technology Center (MTEC); Imperial College London
Type
Article
Source Title
JOURNAL OF MATERIALS SCIENCE
ISSN
0022-2461
Year
2009
Volume
44
Open Access
Green Submitted
Publisher
SPRINGER
DOI
10.1007/s10853-009-3760-9
Format
Abstract
Large deformation and fracture properties of two types of starch gels were investigated through uniaxial compression, single edge-notched bend (SENB) and wire cutting experiments. Tests were performed at various loading rates and for various starch/powder concentrations (%w/w). It was found that starch gels exhibit rate independent stress-strain behaviour but show rate-dependent fracture behaviour, i.e. stress-strain curves at three loading rates are similar but fracture stress and fracture strain increase with increasing strain rate. This is rather unusual and interesting behaviour. SENB and wire cutting experiments also revealed rate-dependent fracture behaviour and that the true fracture toughness (G (c)) values increase with loading/cutting speeds and starch powder concentration. In addition, the G (c) values from wire cutting and SENB tests were in reasonable agreement. The wire cutting process was also studied numerically using finite element techniques. A non-linear elastic constitutive relationship based on Ogden was used to model the starch gels and a frictionless condition was assumed at the wire-starch gel contact interface. A fracture criterion based on maximum principal strain was assumed for the prediction of the steady state cutting force.
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WOS