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Sensitivity calibration of post‐yield strain gauges under cyclic plastic straining
Author(s) -
Rees D. W. A.
Publication year - 1992
Publication title -
strain
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.477
H-Index - 47
eISSN - 1475-1305
pISSN - 0039-2103
DOI - 10.1111/j.1475-1305.1992.tb00800.x
Subject(s) - strain gauge , materials science , sensitivity (control systems) , hardening (computing) , strain hardening exponent , plasticity , linearity , plastic bending , calibration , gauge factor , composite material , structural engineering , levy–mises equations , softening , gauge (firearms) , yield (engineering) , bending , mathematics , metallurgy , fracture mechanics , electronic engineering , engineering , stress intensity factor , medicine , statistics , alternative medicine , bending stiffness , layer (electronics) , pathology , fabrication
A plastic sensitivity calibration procedure is outlined for strain gauges under cyclic, four point bending. Tests show that the gauge resistance changes in an approximately linear manner with longitudinal strain for the first quarter cycle of loading. Calibration curves for subsequent reversals to the direction of deformation display zero‐shift and non‐linearity. Under balanced strain cycling, there is evidence of a cyclically‐stable, sensitivity calibration loop. Theoretical considerations are given in which it is proposed that separate sensitivity factors apply to the elastic and plastic components of strain. It is shown that the plastic sensitivity factor is a function of (i) plastic strain induced hardening and softening in the gauge foil and (ii) any apparent change to the gauge resistivity due to imperfect bonding. The elastic component sensitivity factor equals the manufacturer's value only in the absence of hardening. The two sensitivities may be combined to give a total sensitivity factor when a post‐yield strain gauge suffers elastic‐plastic straining.