Dynamic Photoelasticity Using LED and Polaroid Film

Dynamic photoelasticity relies on high-speed photographic systems to record the fringes in motion. Several systems are being used, but the delayed microflash is widely popular in non-destructive studies due to the high-contrast recording and low cost. Flash lamps and lasers are routinely employed as the light source in these setups. The use of LED as a microflash in such systems is presented. Capability of the system is demonstrated by recording fringe patterns from a photoelastic model under dynamic loading. A high-speed Polaroid film is used for recording the dynamic fringe patterns. Low cost, low power, and simplicity in the experimental setup make it possible to adapt the system to undergraduate laboratories.