A CTOA description of size effects in R-curves for large growth

A conventional 3D finite element model has been made of two different sizes of bend pieces that show a strong effect of size for the J-R-curve when taken to large amounts of growth. The model data has been analysed in terms of a particular definition of the crack tip opening angle (CTOA) for a steady state regime of large growth, by using the plastic component of mouth opening and the position of the instantaneous centre of rotation. The computed and experimental data are shown to he consistent. Taking the CTOA of one size as a datum and using an already proposed rule, CTOA root G = H approximate to constant, allows the size dependant behaviour of the other size to be predicted as approximately inversely proportional to square root of size. Computations can be mede in terms of the combined elastic plus plastic CTOA, without recourse to special elements. The transient regime of small growth is not included in this analysis.