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It has been introduced and analyzed on literature-based relations that calculating the deterioration produced by cyclic loading with normal stresses can be actually calculated. Based on the principle of critical energy, deterioration has been expressed as a power function. The deteriorations thus calculated can be summed up in order to obtain the cumulated effect of the external loadings. There have been established expressions for the deterioration produced by the action of: a single cyclic stress, several blocks of cyclic stresses with normal and/or shear stresses by taking into consideration the cumulated effect of vibrations and/or corrosion, cracked or crack free structures. The relations refer to both samples as well as to actual structures with stress concentrations. One suggested a procedure as to apply the obtained results to the case of random loading of a structure. The calculation examples show how the article makes use of the relations proposed.

The problems of loading superposition of low cycle fatigue, finite cycle fatigue and high cycle fatigue on cracked structure are analyzed. The nonlinear power law behavior of the structure material has been considered. A strength criterion was established for a cracked structure under low cycle fatigue, finite cycle fatigue, and high cycle fatigue loading taking into account the deterioration. On the basis of concept of the specific energy participation and using Basquin's law and Coffin-Manson's law, a general relationship of fatigue life was established in the case of superposition of low cycle fatigue, finite cycle fatigue, and high cycle fatigue loadings on a mechanical structure deteriorated due to cracks. The derived relationships depend on the high cycle fatigue and finite cycle fatigue mean stress and on the low cycle fatigue mean strain, as well as on deterioration. Relationships for the deterioration calculation were established. Experimental work was performed for specimens with cracks, made of steel, statically and cyclically loaded. A numerical example shows how the established relationships may be used.

In this second part of the paper, one puts into evidence the factors wich influence the fatigue resistance and the fatigue limit of materials (the frequency of applied load, mean stress, residual stresses, voids or cracks), as well as the influence of cyclic loading onto the monotonic stress � strain curves properties. On the basis of the principle of critical energy one have been established some relations for the influence of mean stress and residual stress about the fatigue strength and fatigue limit. In the same time one puts into evidence the influence of cracks, of the loading direction and of the type of loading one the fatigue limit.

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