Volume 17, Issue 6 (November 1989)
Rotation Corrections in Three-Point Single Edge Notch Bend Specimens
In elastic-plastic fracture toughness tests of three-point single edge notch bend (3P-SENB) specimens, very ductile materials suffer significant distortions from their initial geometrical configuration, producing large rotation angles of the arms and causing the rollers to move out and detach themselves. These effects should be taken into account when the Unloading Compliance Method is employed to obtain the slow stable crack growth, because the equations are calculated for the initial condition of null rotation angles.
Experimental measurements of the span change for 3P-SENB specimens with different rotation angles and under several conditions were obtained. The results were compared with other authors' results and with those corresponding to CT specimens. Expressions for the corrected values of span and compliance were deduced, and the errors for not using the corrections were estimated. Conditions that give minimal errors were also documented.