Effect of notch configuration and pre-crack length on stress intensity factors

Abstract The determination of stress intensity factors for specimens with pre-cracks is important in fracture analysis. In this paper, the evaluation of stress intensity factors of modes I and II for compact tension specimens is presented. A 3-D finite element analysis (FEA) model using the ANSYS program is constructed for specimens made of different bio-medical materials such as stainless steel, titanium, alumina, high density polyethylene (HDPE) and polymethyl methacrylate (PMMA). Such materials are used for hip and knee replacement and for dental implants. The effects of notch angle, notch tip radius and pre-crack length on the stress intensity factor are studied. The number of elements along the crack front and crack tip is considered and has been varied to determine its effect on the value of the stress intensity factor. It is concluded that, in order to evaluate the reasonable values for the stress intensity factor, the pre-crack lengt should be greater than 10% and 33% of the total crack lengt for modes I and II, respectively. The results for the stress intensity factors K I and K II are obtained using a linear elastic fracture mechanics (LEFM) approach.