Modeling aging effects for structures underposed to the diffusion of an ammalorating fluid

Aging in mechanical structures is due to various environmental attacks (so called, chemical attacks) and operation conditions (mechanical conditions). Chemical attacks are emphasized in extreme environmental conditions such as those in offshore wind structures or in dams and generally in those cases the structures are in the neighboring of the sea. Besides, corrosion is a kind of chemical attack that maybe of different types. Among them, we have: (i) uniform corrosion, in which the corroded areas occur in a manner evenly distributed across the material being attacked and (ii) non-uniform corrosion, or pitting corrosion, which is an extremely localized form of corrosion that leads to the formation of small cavities in the metal. Fatigue is a failure mechanism that involves the cracking of materials and structural components due to cyclic (or fluctuating) stress. Components of a horizontal axis wind turbine and foundations for offshore wind turbines are all under posed to cyclic loadings that are admissible, i.e. they are lower than the maximum possible load. However, if the number of cycles is high, even for a moderately low loading value, the structure may suffer a failure. This condition is expressed by the so called Whöler diagram that, for a given load, it gives the number of cycles at which we have the failure. The aim of the talk is to show how to conceive a universal model for the aging phenomena of structures, that is not only well-posed from a mechanical point of view but also that is able to be used as the basic instrument to design the periodicity for the structural assessment. As an example, we will show both an explicit calculation of the life time of a dam and the derivation of the Whöler diagram. The outlook of this procedure is to conceive a new method for design the life time under aging effects.