The determination of crack bridging forces

A method is presented for determining the bridging tractions acting on the fracture surfaces of cracks from measurements of the crack opening profile. The tractions may be expressed either as a function (x) of position in the crack or a function p(u) of the crack opening displacement. The feasibility of deducing (x) or p(u) from noisy displacement data is demonstrated by numerical simulations. It is found that the most complete information is contained in profiles of cracks growing from notches. Improved estimates of p(u) can also be found by analzying data from several cracks at different stress levels simultaneously.