A Two-Parameter Description of the Behaviour of a Process Zone at a Crack Tip: Part II — Determination of the Parameters
An earlier paper (Part I) has shown how key parameters associated with the uniform stress process zone model of a crack: crack tip opening displacement, process zone size, crack opening area and the effective opening area of the process zone, depend upon parameters that are associated with the relevant terms in the expansion of the expression, for the purely elastic situation, for the relative displacement of the crack faces or the stress ahead of an elastic crack. The earlier paper focussed upon the case where the non-linear (with regards to applied stress) contributions to the crack-process zone parameters were determined to the first two terms in increasing powers of the applied loading stress parameter. These terms depend upon the first two terms in the expressions for the crack face relative displacement on the stress ahead of the crack in the elastic situation. The first of these terms is related to the stress intensity factor. In this paper we show how the parameter g0, which defines the second term, can be determined for some idealised situations.