Crack propagation at supersonic velocities

✍ Scribed by D. A. Shockey; S. Winkler; D. R. Curran

• Book ID: 104657392
• Publisher: Springer Netherlands
• Year: 1969
• Tongue: English
• Weight: 40 KB
• Volume: 5
• Category: Article
• ISSN: 1573-2673
• DOI: 10.1007/bf00190967

✦ Synopsis

Evidence implying crack velocities in KCI crystals an order of magnitude greater than the velocity of the fastest elastic wave has been obtained. Fracture was produced by irradiation with a giant impulse laser, and average crack propagation velocities of the order of 104 to 10 5 m/sec were inferred from the ~izes of cleavage cracks in photographs taken approximately 80 nsec after beginning of irradiation. These results are surprising since supersonic crack velocities were heretofore theoretically and experimentally unknown.

The ultra-high crack speeds seem to result from a rapidly expanding plasma produced within the crystal at the focal point of the laser beam which supplies energy to the crack front at unusually high rates. A theoretical model has been developed which predicts the crack length-time history to be expected for a given energy pulse from the laser. An interference technique is presently being used in an effort to obtain several crack velocity measurements as the crack propagates, and thus experimentally check the theory [I, 2].