Development of procedure for low-constraint toughness testing using a single-specimen technique

Abstract

This study investigated surface circumferential cracks in pipes under strain-based designs with clamped single-edge tension specimens. A test procedure for single-edge bend and compact tension specimens was developed for use in J-resistance tests with single specimen techniques. The finite element analysis (FEA) method was used to develop equations for the evaluation of J-integrals from the area under the plastic crack mouth opening displacement (CMOD) curves and the evaluation of crack length from unloading compliance. The procedure was then compared with standard testing methods of J-integrals with crack growth correction, crack length evaluation, the correction of compliance for rotation. Initial and final crack length evaluation methods were compared with optical 9-point techniques for broken specimens. The test methods will be expanded to include crack tip opening displacement and the design temperatures of pipelines. 16 refs., 7 tabs., 21 figs.