Dynamic measurements with a luminescent photoelastic coating

Abstract

The luminescent photoelastic coating (LPC) technique optically measures full-field, in-plane strain and principal strain directions on specimens of interest. Typically, a circularly-polarized, continuous, blue-light source is used to excite the coating. The resulting emission polarization, and, hence, emission intensity when viewed through an analyzer optic, is a function of the absorption, luminescence, and surface strain. This research thesis focuses on the dynamic application of the technique, specifically cyclic-load cases as the image intensity is too low for the camera to accurately capture transient-load cases. The dynamic tests involved bar specimens and square-tube specimens loaded at 1 Hz and 10 Hz. Instead of continuous excitation, strobed excitation was phase-synchronized with the frequency of the specimen. The experimental set-up and results are discussed.