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The effective stress values have been defined, in order to find a measurement of the stress field
directly related to the initiation of a failure mechanism, usually a fracture or fatigue crack initiation. This paper
investigates several definitions of effective stress values and applies them to different stress parameters, as well
as stress invariant or strain energy density components. In particular, this work examines the effective values
not only at the tip of a stress raiser, but also in the surrounding material. The final aim is to understand the
relationship between the actual distribution of effective values and the real failure initiation point, i.e. to verify if
the location of maximum values of effective stress parameters is actually the position of the failure initiation.