In linear-elastic fracture mechanics (LEFM) the neartip-field equations for stress and displacement are developed by treating the crack mathematically as a branch cut. However, when natural cracks are loaded with opening mode loads, or when machined slots are used to simulate cracks of specified crack-front shape, finite-root radii exist at the crack tips, and, due to finite deformations ~ and crack-tip blunting, 2 a nonlinear zone will arise inside the LEFM zone. Moreover, depending upon the size and shape of the body and the distribution of the remotely applied loads, the outer reaches of the LEFM zone will be limited either moderately or severely. This means that the LEFM zone of interest to fracture mechanicians for extracting estimates of the stress-intensity factor (SIF) lies between a near-tip nonlinear zone and one controlled by the nonsingular part of the stress field. Techniques for extracting the SIF from photoelastic data have been described by Irwin, 3 Bradley and Kobayashi, 4 Smith, 5,6 Theocaris, 7 Dally and Sanford 8 and Rossmanith and Irwin. 9 Most of these techniques rely upon measurements outside of:the LEFM zone as well as within the zone in order to obtain data for complete fringe loops or to take advantage of special analytical relationships. These methods have been applied principally to two-dimensional propagat ing or crack-arrest problems to date. Over a decade ago, the first author and his colleagues began to study ways of combining the LEFM equations with the 'frozen-stress' photoelastic method with the goal of obtaining estimates of SIF distributions along the flaw border for three-dimensional cracked-body problems. The initial approach was confined t o opening mode loading and is described in Ref. 5. It has since been modified '~ and extended to mixed-mode problems: ,~' '~2 The constraints associated with the frozen-stress method are well known: it is restricted to the elastic behavior of an incompressible material. The insertion of cracks into a three-dimensional body for photoelastic analysis involves a number of additional considerations.