Calibration and validation of extended back-face strain compliance for a wide range of crack lengths in SENB-4P specimens

Compliance equations based on back-face strain or crack mouth opening displacement, and potential drop techniques are widely used to calculate fatigue growth rate. Standard ASTM E647 for rate testing does not include compliance single edge notched four-point bending (SENB-4P) specimens. Equations developed finite element (FE) analysis have been reported in literature; however, they limited the long propagation regime (i.e., relative length ratios a/W > 0.15). No relations physically short were found literature. This work reports a complementary numerical-experimental study towards development of with an extended application range terms length. FE simulations calibrate equation calculation 0.05 ? 0.5 SENB-4P Four point tests performed SENB specimens extracted from 50 mm thick welded steel plates. Direct current (DCPD) monitoring was as benchmark validation lengths determined gage.