Volume 5, Issue 10 (November 2008)
The Significance of a Crack Growth Law for a C(T) Fracture Specimen Undergoing Stable Crack Extension
A new method of construction of the J-R curve has been proposed recently that makes use of a postulated crack growth law relating stable crack extension, Δa, to plastic displacement, vpl. An analytical treatment of both the J-Δa curve and the force-displacement, P-v, curve, is now possible even under circumstances in which the sole inputs are the P-v curve and the initial and final crack size values. Based upon this crack growth law concept, and on the common and the concise format equations of Donoso and Landes, an alternative way of estimating the amount of stable crack growth is presented. This alternative method, which allows for the evaluation of the crack size at any value of force or displacement along the P-v curve, has been applied to some examples of C(T) fracture test specimens that have crack extension values obtained by the unloading compliance method. The results are quite encouraging, and the method is extended here to cases in which there are no crack extension measurements available.