symposium 1 - Crack Paths 2021

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Notch fatigue strength in the presence of intrinsic defectiveness and/or complex multiaxial loading
Matteo Benedetti, University of Trento, Italy
Ciro Santus, University of Pisa, Italy
Filippo Berto, Norwegian Institute of Science and Technology, Norway
Keywords: notch fatigue, defects, multiaxial fatigue, residual stresses, additive manufacturing
Notches are geometrical details perturbing the lines of force flow in components subjected to mechanical loading. The resulting amplification of the stress field in their neighborhood impacts detrimentally on the fatigue strength. Clearly, a reliable design of machine parts requires robust notch fatigue assessment methods. These include traditional methods codified in machine design manuals and based on correction coefficients accounting for the geometrical stress concentration factor and the material’s notch sensitivity. Fracture mechanics, critical distance or strain energy density methods have been devised for more accurate fatigue calculations.
The present symposium is aimed at gathering researchers interested in further developing notch fatigue assessment methods to face currently unclear issues, like the effect of intrinsic defectiveness and multiaxiality on the notch fatigue strength. Defects, such as surface scratches and roughness, non-metallic inclusions, pores, foreign object damages, play a crucial role in fatigue crack initiation and propagation. Nowadays, the interest in incorporating the effect of defects into the fatigue design has further increased with the advent of additive manufacturing (AM) technologies, which, on one side, permit larger design freedom, on the other one, introduce into the component defects in the form of surface roughness, pores and lack of fusion. How to deal with the concomitant effect of defects at the microscopic level and of notches at the macroscopic one is however not straightforward. Moreover, the presence of notches produces a local multiaxial stress field even under the action of an external uniaxial loading condition. In real applications, loading application can be even more complex, because of the concomitant application of multiple loading modes and/or the presence of a residual stress field.
We hope to receive many contributions to the present Symposium so as to stimulate essential collaborations between materials scientist, technologists and mechanical designers.

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