Experimental evaluation of rotational factor in blunt notched bend geometry

Considerable ambiguity is still associated with the values of rotational fa ctor (r) that allows inference of displacement values at the crack tip from crack mouth displacement measurement. An empirical modelling on r involvin g plastic bend angle. plastic zone size and notch face displacement has rec ently been established for situations both well below and around general yi eld. The present work attempts at experimental in three point bend blunt no tched geometry. Experimental r values are obtained from displacement measur ements at several points across the notch face using SEN specimen. The rota tional factor is found to be in the range of 0.26 - 0.28 and 0.50 - 0.56 re spectively for elastic and elastic-plastic situations. An attempt is also m ade to investigate the r values ill slow crack growth situations where the hinge point is found to shift gradually away from the original notch tip.