Abstract: The additional displacement method is developed for damage coupled elasto plastic stress analysis and life estimate for metallic structural components in the process of crack initiation. Damage is described with a scalar. The basic formulation is established in terms of the range of variation about related fields. The damage of the critical point is regarded as a generalized time scale instead of the cycle number. The local behavior of damage is rather fully used in the study of notched sheets. The required integration is performed only within the damage zone and the damage influenced zone, which are only small parts of the structure configuration. The amount of computational work of this scheme is much less than that of ordinary numerical analysis of the whole field. Examples show that the computed results agree well with experimental ones. This approach exhibits some referential value for solving other problems with locally coupled effects.

Key words: damage mechanics, fatigue crackinitiation, life estimate, additional displacement method