Reflective photoelasticity and holo-interferometry applied to stress wave propagation

The principal stress distribution over a section of a polyester model of a semi-infinite plate during the propagation of a stress wave has been determined experimentally. The stress pulse was generated by the impact of a pendulum hammer. Two external suitable trigger mechanism were used to trigger a double-pulse Ruby laser (0.5 Joule per pulse) at pre-determined intervals. One surface of the model was made fully reflecting so that by means of reflective holo-interferometry of that surface and reflective photoelasticity through the other surface of the model the isopachic and isochrometic fringe patterns were recorded at different time delays after impact.