An experimental technique to measure the thickness of luminescent photoelastic coatings

Luminescent photoelastic coating (LPC) methods are used to measure the full-field shear strain and its principal direction. These methods apply a liquid LPC onto the surfaces of the structures to be measured. To correct the effects of coating thickness non-uniformity on the quantitative shear strain measurements, a non-contact method is proposed for coating thickness measurements. The proposed method establishes a linear calibration curve between the thickness and the luminescent signal intensity of the test coating. The results show that the linear calibration curve of the intensity and the thickness of the LPC can be obtained by incorporating an appropriate concentration of the luminescent dye into the photoelastic coating. The correlation coefficient of this linear calibration curve is more than 0.999.