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NEW PROCEDURE FOR ESTIMATING THE MODULUS OF DEFORMABILITY OF CHEESE FROM UNIAXIAL COMPRESSION TESTS
Author(s) -
WATKINSON PHILIP J.,
JACKSON L. FRASER
Publication year - 1999
Publication title -
journal of texture studies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.593
H-Index - 54
eISSN - 1745-4603
pISSN - 0022-4901
DOI - 10.1111/j.1745-4603.1999.tb01408.x
Subject(s) - inflection point , compression (physics) , strain (injury) , strain rate , modulus , materials science , mathematics , fracture (geology) , composite material , stress (linguistics) , deformation (meteorology) , geometry , medicine , linguistics , philosophy
The gradient of the inflection at the lowest strain in a stress versus strain curve was used to estimate the modulus of deformability (E d ) of cheese from the commonly used uniaxial compression test. The procedure required a sufficiently high sampling rate (e. g. 50 Hz at an initial strain rate of 0.0332 s −1 ) to give data that provided fine structure to the measurements which is not usually reported. This procedure was based on the empirical observation that there was an initial concave up region prior to the usually reported concave down region of the curve for all samples studied. Numerical estimation of the gradient was used to locate the inflection point, and to estimate the gradient at that point. The procedure gave a well‐defined measurement in the region of interest at small strain. It did not assume that all samples had the same strain region for compaction‐dominating and fracture‐dominating processes. Thus, in effect, it took account of the different strains at which E d should be measured and eliminated differences in E d between samples induced by differences in these processes. This procedure was compared with three existing procedures, for three cheeses. The procedure used responded differently to each cheese at the 1 % level. Values of E d from the inflection point were similar to those from the gradient over 0.5 to 1.5 times the inflection strain, and higher than those from the gradient over 0 to 0.04 strain or from the linear term in a fiph order polynomial fit to the data up to fracture. The ranking of Ed for each cheese was the same for each procedure and the relative magnitude of Ed for each cheese was similar for each procedure.