Partially polarized fluorescence of a mechanically stressed polyurethane disc

This study theoretically and experimentally investigates the effect of partial polarization of fluorescence in a polyurethane disk under diametral compression. The degree of fluorescence polarization is described using a dipole approximation and a statistical bimodal Fisher distribution model that characterizes the preferential orientation of dipoles. An experimental setup with normal excitation and observation of photoluminescence is proposed, allowing visualization of the preferential orientation field of the dipoles. The degree of fluorescence polarization in the compressed polyurethane disk was experimentally studied, revealing agreement between the visualized data and the theoretically predicted directions of principal stress planes according to elasticity theory. The aim of the study is to establish the foundations of a “polarization-luminescent method” for remote and continuous monitoring of the stress-strain state.