TY - JOUR
T1 - Uniformity of axial displacement in element testing
AU - Kim, Woosung
AU - Labuz, Joseph
AU - Chadbourn, Bruce
AU - Loken, Marc
PY - 2008/5
Y1 - 2008/5
N2 - Uniform axial deformation is a basic assumption in element testing, where axial strain typically is determined from displacement measurements. In applying force through rigid platens, however, some rotation may occur such that the fundamental stress field is perturbed. Thus, nonuniformity among measures of axial displacement may be present, and the response may consist of a component due to uniform deformation and a component due to rotation. To estimate this nonuniformity for cylindrical specimens, at least three sensors are needed, and in general, the axial strain cannot be estimated without error from only two sensors. For equiangular placement of three sensors, it is shown that the mean of the displacement readings is equal to the displacement from the uniform component. The rotation does not affect the average value, but the rotation must be calculated to estimate the nonuniformity. The ratio of the measured maximum and minimum displacement does not provide an objective evaluation.
AB - Uniform axial deformation is a basic assumption in element testing, where axial strain typically is determined from displacement measurements. In applying force through rigid platens, however, some rotation may occur such that the fundamental stress field is perturbed. Thus, nonuniformity among measures of axial displacement may be present, and the response may consist of a component due to uniform deformation and a component due to rotation. To estimate this nonuniformity for cylindrical specimens, at least three sensors are needed, and in general, the axial strain cannot be estimated without error from only two sensors. For equiangular placement of three sensors, it is shown that the mean of the displacement readings is equal to the displacement from the uniform component. The rotation does not affect the average value, but the rotation must be calculated to estimate the nonuniformity. The ratio of the measured maximum and minimum displacement does not provide an objective evaluation.
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M3 - Article
AN - SCOPUS:54949126388
VL - 31
SP - 274
EP - 278
JO - Geotechnical Testing Journal
JF - Geotechnical Testing Journal
SN - 0149-6115
IS - 3
ER -