Improvement to Crack Retardation Models Using 'Interactive Zone' Concept

초록

The load interaction effect can be best ilustrated by the phenomenon of overload retardation. Some prediction methods for retardation are reviewed and the problems discussed in the present paper. The so-callde "under-load" dffect is also of importance for a prediction model to work properly under random load spectrum. The concept of "interactive Zone(IZ)" fully considering reversed plasticity during unloading is discussed. This IZ concept can be combined with existion models to derive some imporoved models that can naturally take account of the under-load effect. Some simulations by IZ improved models for test under complex load sequences including multiple overloads and both over/under loads are compared with test results. It is seen that the improvement by IZ concept greatly enhanced the ability of existing models to accommodate complex load interaction effects.