Pubblicazione:
Cyclic plasticity and low cycle fatigue behaviour of laser-powder bed fusion 316L steel at different length scales
Cyclic plasticity and low cycle fatigue behaviour of laser-powder bed fusion 316L steel at different length scales
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Data
2025-03-27
Autori
PELEGATTI, MARCO
Titolo del Periodico
ISSN Periodico
Titolo volume
Editore
Università degli Studi di Udine
Progetti di ricerca
Strutture
Fascicolo Periodico
Abstract
Investigating the structural integrity of components produced by additive manufacturing (AM) presents unique challenges, particularly when the component is subjected to cyclic loads. Process-induced defects and a peculiar non-equilibrium microstructure strongly influence the fatigue properties. These challenges are further amplified when architected cellular materials (or cellular structures) are involved, as they introduce a structural vulnerability due to the notches in the cell shape. In the low cycle fatigue (LCF) regime, the involvement of plastic strains adds an extra layer of complexity, given the intricate relationship between microstructure and cyclic response.
Within the context of promoting AM metals in fatigue-related applications by facing the abovementioned challenges, this thesis focuses on the LCF behaviour of 316L steel produced by laser-powder bed fusion in bulk and cellular forms. To describe the LCF properties of cellular structures, the LCF behaviour of the base material was thoroughly investigated. An LCF test campaign was conducted on cylindrical specimens to ensure accurate modelling. The obtained stress-strain response serves as the basis for correctly calibrating the constitutive models of cyclic plasticity. Furthermore, the fatigue tests allowed the resistance curve to be characterised, which is necessary to estimate the life of cellular materials. Following the characterisation of the base material, the cyclic elastoplastic response and fatigue resistance of two cellular materials were investigated through strain-controlled LCF tests. The experimental data were then compared with the results provided by finite element simulations, in which the fatigue strength was estimated via a criterion based on the strain energy density averaged in a control volume. Finally, further research was conducted on the role of the microstructure in the mechanical behaviour and damage of the base material during the various phases of the cyclic elastoplastic response. Using investigation techniques combined with modelling tools such as crystal plasticity has shed light on the relationship between microstructure and mechanical properties, which helps optimise the mechanical response of the base material and, consequently, the cellular material.
Descrizione
Parole chiavi
Low cycle fatigue,
Cyclic plasticity,
316L stainless steel,
Cellular material,
3D printing (AM),
Settore ING-IND/14 - Progettazione Meccanica e Costruzione di Macchine