CRITICAL EXPERIMENTS, MEASUREMENTS AND ANALYSESnTO ESTABLISH A CRACK ARREST METHODOLOGY FOR NUCLEAR PRESSURE VESSEL STEELS SECOND QUARTERLY PROGRESS REPORT ON TASK AGREEMENT NO. 62

摘要

Work is in progress to validate the conducting-grid method of measuring velocity. Eddy current-type proximity detectors have been successfully adapted for measuring test piece and testing machine movements during the period of crack propagation and arrest. Studies of the effect of side grooves in rectangular DCB specimens confirm that grooves with depths representing up to 60% of the cross section have no significant effect on either KID OR KIa measurements. Wedge-angle has also been varied systematically thereby producing a ~10-fold and~ lOO-fold change in the compression load and stored energy, respectively, at the onset of propagation. These experiments reveal a small effect of wedge angle on the initial velocity and KiD-measurement, but substantial differences in the amount of stored energy exchanged between the test piece and the machine prior to crack arrest. Preliminary results for the KID-crack velocity dependence of the 0-1,4340 and A533B steels are presented.