AN EXPERIMENTAL-NUMERICAL ANALYSIS OF FRACTURE PROCESS ZONE IN CONCRETE FRACTURE SPECIMENS

Moire interferometry was used to determine the distribution of the crack opening displacement (COD) along the process zones of stably growing cracks in five crack-line wedge-loaded, double cantilever beam (CLWL-DCB) specimens and four prenotched three point bend specimens. An optimization procedure, employing the generation phase of a finite element analysis, was used to best fit a postulated continuous crack closure stress vs COD relationship to the experimental results. The resultant continuous function agreed well with the three straight-line segments of the crack closure stress vs COD relationship anticipated for these specimens and derivable previously only by experimental-numerical techniques. The controversy regarding the specimen geometry dependency of the crack closure stress relationship was effectively resolved by these limited tests. The fracture responses of these two types of specimens were modeled using the application phase of a finite element analysis. © 1990.