Study of crack-tip motion in dynamic fracture by microscopic time-resolved holography

Autor: J. Scott Steckenrider, James W. Wagner
Rok vydání: 1995
Předmět:
Zdroj: International Journal of Fracture. 73:213-222
ISSN: 1573-2673
0376-9429
DOI: 10.1007/bf00037644
Popis: A novel laser system has been designed and developed for the time-resolved holographic analysis of dynamic crack propagation in thin (150 μm) glass plates. The system provides a frame-to-frame resolution of from 28.3 to 161.6 ns, with a spatial resolution of better than 25 μm. Holographic analyses were conducted using both diffuse and direct laser illumination, demonstrating a broad range of applicability for this method. A series of specimens with pre-crack lengths of from 3.5 to 10.5 mm were tested using various pre-load levels and crack-growth-initiating explosive sizes. All specimens exhibited similar dynamic fracture behavior, particularly those outside of the region of shock of the initiating explosive (those of the longer pre-crack set). A best-fit to the theoretical prediction for mode I crack growth revealed a good match to the case for a specimen ‘overloaded’ by 64 percent. However, no variation with applied load was evident, indicating that an immediate acceleration to a velocity of ≈ 1200 m/s (near the empirically determined terminal velocity) was the more plausible fit. Since the terminal velocity was approximately the same for all specimens, this investigation also demonstrated that the terminal velocity is independent of crack-tip stresses, even for the most extreme explosive pulses.
Databáze: OpenAIRE
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