Alternative to strain measurement

It has been well documented that microstructural effects cause ambiguities in strain measurement. Moreover, extreme sensitivity is required to measure strain in very thin structures. That it varies sharply across structural sections of interest and cannot be measured along the neutral plane of bending are additional reasons to reassess the suitability of strain as the usual measurand of choice for evaluation of structural deformation. We show that on all these accounts the alternative of measuring deformation curvature with a recently derived device called a curvature gauge offers conceptual advantages over the traditional practice of strain measurement. (C) 2003 Society of Photo-Optical Instrumentation Engineers.