Strain field associated with brittle-fracture propagation in wide steel plates

The results of an experimental investigation concerned with the study of the strain field surrounding a brittle fracture propagating across a wide steel plate are presented in this paper. The data were obtained from tests of 6-ft wide steel plates that were instrumentated to measure surface strain and crack speed. The plates were tested at an average net applied stress of 19,000 psi, a temperature of about ?5° F, and with the notch-wedgeimpact method for fracture initiation. Several plates were tested under similar conditions and the results were superimposed to give a representative picture of the strain distribution on the surface of a plate in the region of the tip of a propagating fracture. Contours of the maximum principal strain for various lengths of crack are presented. The studies indicate that for this particular specimen geometry and associated test conditions, the strain field surrounding the tip of the advancing fracture remains essentially unchanged after traversing about one-third of the width of a 6-ft wide plate.