Pages 155-156
High-speed optical interferometry is applied to measure dynamic stress intensity factor of fast propagating cracks. The method of interferometry gives the true value of dynamic stress intensity factor when the measurement is carried out in the singular stress field that satisfies the plane stress condition. However, one cannot obtain the true K-value if it is measured within the three-dimensional stress field in the vicinity of the crack tips. In order to obtain the true value of dynamic stress intensity factor in the three-dimensional stress field, the present study makes a correction equation using the K-values measured by the interferometry. It is found that the measurement accuracy is about ±20% in the three-dimensional stress field when a crack is propagating in a PMMA specimen at a speed of 600m/s.
