A recently developed experimental method, stress intensity factor tracer, is extended to measure the strength, J, of the HRR singularity for near-tip plastic deformation. Focal-plane mapping of the HRR field shows that the light intensity, I, collected on a finite area of the focal plane has a simple relationship with J as I = βJ2n/(2n+1). The constant, β, is a product of several experimental parameters and “n” is the hardening parameter of a power-law hardening material. The focal-plane mapping technique is also capable of estimating the shape and size of the HRR-field dominant region for a relatively thin (<10mm) metallic specimen. In addition, a continuous trace of the J variation can be monitored using a single, stationary photodetector. Because the measurement value of this method is independent of crack-tip motion, the transition of HRR singularity from stationary to moving can also be studied. In this paper, the theoretical analysis of the method is presented.

This content is only available via PDF.
You do not currently have access to this content.