FATIGUE CRACK PROPAGATION IN ALUMINIUM AND PMMA.

The semi-empirical formulation initially proposed by Paris et al. has received popular acceptance. The applicability of the above fatigue law has subsequently been examined for various materials under different loading conditions for metals and non-metals. It is necessary to express the FCP relationship in terms of the strain energy release rate ( DELTA G) instead of the stress intensity factor as the former includes Young's modulus which makes it possible to achieve a common intercept. Both Forman's proposal and Sutton's proposal fail to satisfactorily characterize the combined FCP of aluminum alloys and PMMA with respective correlation coefficients of 0. 883 and 0. 753. The success of a new FCP formulation to characterize both the aluminum alloys and PMMA in a diagram is demonstrated.