Determination of the Optical Constants of Caustics under Dynamic Loading Using a Concentrated Load

A new technique is proposed for evaluating the optical constants of caustics under dynamic loading. In this technique, the optical constants are determined from the caustic pattern under a concentrated load and the dynamic value of the concentrated load, which is obtained using strain gages bonded to the surface of the falling weight. The optical constants of caustics c0 for several polymers are accurately evaluated from the caustic pattern formed by a concentrated load acting on a half plane, and the dependence of c0 on the loading rate is determined. The results show that the value of c0 decreases considerably with increasing loading rate in Plexiglas and Araldite D containing 30% softening material. On the other hand, the values for polycarbonate. Araldite B and Araldite D not containing softening material decrease slightly with increasing loading rate.