Calibration of high-sensitivity photoelastic coating materials
such as polycarbonates and the rigid epoxies is usually accomplished by employing a cantilever beam in bending. The coating is placed on one side of the beam, and the beam is
strained by dead weights or a predetermined deflection F applied on the free end. Accurate measurement of the fringe order N with a
at a number
of increments of load, will generate graph of F versus N, and best fit straight line is constructed through the data points. The slope of this line gives the best value N/F to be used for the calibration constant. For further
reading, click here
for Calibration of PhotoStress® Coatings (Technical Note TN-701).