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13 August 1993 Behavior of materials at dynamic stress conditions using laser-induced shock waves
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A high irradiance short pulsed Nd:glass operated in TEM00 mode was used to generate shock waves in different materials to study their behavior at dynamic stress condition. Dynamic fracture at hypervelocity impact regime was observed as a result of reflected shock waves as tensile waves from the back surface of the samples. Damage development from incipient spallation to complete sample perforation were obtained for planar and hemispherical shock waves. Maximum elongation at fracture at ultra high strain rate was measured for several metals. Shock wave attenuation and dynamic strength were evaluated for metals and composites. A linear dependence was obtained for the pressure decay as a function of target thickness for planar shock wave. The experimental results of threshold for spall and spall width at this energy were compared with numerical simulations. The laser pulses were also used to generate hemispherical shock waves in targets (focal spot smaller than target thickness). A linear experimental relationship was obtained between laser energy for threshold spall conditions and the cubic target thickness. This relation is equivalent with the propagation of a strong point explosion where the internal energy per unit volume of the shocked materials is constant. The shock wave was modeled by an expanding pressure front, which creates micro-damage in the laser impacted layer and extrudes a bulge at the far surface. The calculated bulge size compares well with that observed by us for metal-adhesive-metal sandwiches. The micro-defects joining into macro-damage or fracture can be described by percolation theory.
© (1993) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Irith Gilath, S. Eliezer, T. Bar-Noy, R. Englman, and Z. Jaeger "Behavior of materials at dynamic stress conditions using laser-induced shock waves", Proc. SPIE 1972, 8th Meeting on Optical Engineering in Israel: Optoelectronics and Applications in Industry and Medicine, (13 August 1993);

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