An Evaluation of the Single Edge Notched Bend Specimen

Abstract

This work is the first of two complementary tasks to compare Master Curve To temperature results between single edge notched bend specimens and compact tension (bend) specimens. The investigation was undertaken because of an unfavorable, non-conservative bias when testing with precracked Charpy specimens. The present report involves calibration work in which the computational validity of J-integral determinations for small specimens with small ligaments is checked. Also, the constraint characteristics of various specimen types and sizes are evaluated using key curves, plastic-zone size estimates, and notch strength determinations. The results indicate that J-integral solutions for small specimens of Charpy size retain comparable J-integral validity the same as larger specimens. The constraint situation was not equally straight forward. There are two phases in plastic deformation-one is crack tip plastic zone development only, phase 1, and plastic hinging, phase 2. From a constraint gradient perspective, these two phases are not alike. Bottom line is that precracked Charpy specimen KJc values are under extensive phase 2 deformation and have the highest notch strength among the other geometries evaluated. This observation conflicts with mechanics based constraint results used to explain why there is a To temperature bias when using precracked Charpy specimen KJc data.