Abstract
Holographic caustic method is applied to measure the dynamic stress intensity factor of fast propagating cracks not only in the region of the singular stress field of plane stress but also in the 3-dimensional stress field in the vicinity of the crack tips. The caustic method is based on the assumption that the initial curves of caustics are in the singular field of plane stress, hence, it doesn't give the correct values of the stress intensity factor if the initial curves are in the 3-dimensional stress field. In order to obtain the correct K-values in the 3-dimensional stress field, two correction curves are examined and are compared with the correction curve obtained from stationary cracks. It is shown that the correction curves obtained from the measured K-values of fast propagating cracks are approximately equal to that obtained from the stationary cracks within the accuracy of measurement.
