Application Of Laser Interferometry For Study Of Two-Dimensional Shock Wave Effects

The primary emphasis of this paper is to show that the laser interferometric technique can be a valuable electro-optical measuring tool in the study of material response to the 2D shock wave phenomena found in hypervelocity impact. Preliminary experiments conducted at Effects Technology, Inc. on several nosetip and heatshield materials indicate that laser interferometry is a useful high speed measurement technique for the study of two-dimensional shock wave effects. The two-dimensional shock wave generators for these initial tests were single particle hypervelocity impacts. The specimens were impacted normal to the front surface by a 1000 pm glass sphere at velocities ranging from 3660 m/sec (12,000 ft/sec) to 4880 m/sec (16,000 ft/sec) while the laser beam continuously monitored the rear surface of the specimen. The laser interferometer records the free surface motion of the material as the transmitted shock wave is incident on the rear surface. Consequently, a graphical representation of the shock pulse reaching the specimen free surface can be reconstructed from the interferometric data record. Data processing and analysis of this type leads to the characterization of the dynamic two-dimensional shock wave response of the material.