Description of Crack Growth on the Basis of the Strip-Yield Model for Computation of Crack Opening Loads, the Crack Tip Stretch and Strain Rates.

摘要

Nowadays, the application of the STRIP-YIELD model for computation of crack opening load levels is well known. In this paper the incremental formulation of a fatigue crack growth law is used to demonstrate the role of the crack opening load level in time independent fatigue crack growth. Less known is the ability of the STRIP-YIELD model to define the strain rate at the crack tip. The model discussed in this paper is a mechanical model. Physical aspects other than the strain rate, the loading frequency and load wave shape are not modelled in an explicit way. Hence, the model is valid for specific environment/base metal combinations. However, in a consideration of the effects of small variations of environment, temperature and other variables on the crack growth rates, it can be used as a reference solution. The fatigue crack growth model has been implemented in the NASGRO (ESACRACK) software. The time dependent part is still subject of further evaluation.