Revisit to the determination of stress-intensity factors and J-integrals using the caustics method

摘要

Applications of the optical (shadow) method of reflective caustics to measurement of the stress-intensity factor andJintegral in various specimens are investigated. The necessary experimental requirements to help determine accurate stress-intensity factor andJintegral are described. The ratios ofro(radius of initial curve)/rp(plastic-zone size) andro/t(thickness of specimen) are found to be very important experimental parameters to obtain meaningful stress and/or strain intensities surrounding crack tips. The appropriate ranges to determine accurate values of stress-intensity factor andJintegral for polycarbonate (compact tension) and aluminum (c-shaped tension) specimens are presented.