Close-field optical analysis of an explosive-loading function - Dynamic photoelasticity methods were used to investigate the formation of a stress wave in a region very close to an explosive detonation in a two-dimensional model. Results provide an accurate description of the loading function for use in future analytical and experimental studies

This research program was conducted to study the formation of a stress wave resulting from the detonation of an explosive charge in a circular hole in a large thin plate. Dynamic photoelasticity methods were employed. The isochromatic-fringe patterns were recorded with a Cranz-Schardin multiple-spark camera operating at a framing rate of 500,000 exposures/second. Experimental procedures developed during the course of the investigation eliminated fracturing of the model in the vicinity of the explosive and permitted recording of the dynamic fringe patterns at the boundary of the hole during the entire period of loading. Results of the study provide a realistic pulse shape for use with theoretical solutions to wave-propagation problems when comparisons are made with experimental solutions to the same problems obtained by dynamic photoelasticity means. Propagation and attenuation characteristics of the stress wave in the close field were obtained and compared with previous results obtained by extrapolation from farfield information. An explanation is provided for the high degree of reproducibility of explosive loadings and for the uniformity in amplitude of the stress wave produced in photoelastic models by different amounts of explosive