Boundary identification criteria and geometry analysis of Al 7050 stretch zone from elevation profiles

This article describes the development of a method for analysis of the shap e of the stretch zone surface based on parallax measurement theory and usin g digital image processing techniques. Accurate criteria for the definition of the boundaries of the stretch zone are established from profiles of fra cture surfaces obtained from crack tip opening displacement tests on Al-705 0 alloy samples. The elevation profiles behavior analysis is based on stret ch zone width and height parameters. It is concluded that the geometry of t he stretch zone profiles under plane strain conditions can be described by a semi-parabolic relationship. (C) Elsevier Science Inc., 1999. All rights reserved.