Applicazione di stati tensionali non locali per la previsione della vita a fatica. Application of non lpcal stressed field for the prediction of fatigue life.

In the past three years, it has conducted the research activity on the study of the materials resistance, focusing on the technique useful to estimate the resistance value in the linear elastic field in the presence of notch or weldment. In this cases there is a point in the material where the tension reach very high level related to the net tension, this phenomena stress a lot the material that decrease its resistance. It is not always easy calculate this value of tension, especially when the notch is very sharp the value of tension in the tip reach an incredible huge value: according to the theory, the value at the tip of the crack (for example) is infinite. In the practice, this value is useless, so it needs a methodology that focus not on the maximum point, but on the surrounding field with a certain average. The implicit gradient, with a second order differential equation, allow to calculate a local value of tension by a non-local stress field, by that it is possible to compare the value given by the method with the reference resistance of the material.