Role of porous microstructure on dynamic shear localization and ductile failure

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dc.contributor.advisorRodríguez-Martínez, José A.
dc.contributor.authorAmbikadevi Rajasekharan Nair, Vishnu
dc.contributor.departamentoUC3M. Departamento de Mecánica de Medios Continuos y Teoría de Estructurases
dc.contributor.funderEuropean Commission
dc.contributor.tutorRordríguez-Martínez, José A.
dc.date.accessioned2024-06-17T09:02:22Z
dc.date.available2024-06-17T09:02:22Z
dc.date.issued2024-01
dc.date.submitted2024-02-14
dc.description.abstractThis doctoral thesis aims to provide a comprehensive analysis of the role of porous microstructure on dynamic shear localization and ductile failure. For this purpose, a computational approach was developed that includes large-scale 3D finite element models incorporated with actual porous microstructures that are derived from different additively manufactured materials. This is the distinctive feature of the numerical simulations conducted in this study, in which a large population of voids that are statistically representative of the actual porosity in 3D-printed metals has been included. Additional microstructures varying the void volume fraction, the mean and standard deviation of the size distribution of voids were generated, enabling a systematic parametric analysis of the microstructural features. Finite element simulations of multiple shear bands formation in radially collapsing thick-walled cylinders and shear band formation in thin-tubes subjected to dynamic torsion were performed to investigate the effect of spatial and size distribution of voids on dynamic shear localization. The numerical results demonstrate that microstructural porosity promotes dynamic shear localization, determining preferential sites for the nucleation of the shear bands, accelerating their development, and tailoring their direction of propagation. Specifically, collapsing thick-walled cylinder calculations bring out that, for a given void volume fraction more shear bands are nucleated as the number of voids increases, while the shear bands are triggered earlier and develop faster as the size of the pores increases. Moreover, the numerical results for porous thin-tubes subjected to dynamic torsion quantitatively show that the size of the largest pore is a main microstructural feature controlling the specimen ductility. Furthermore, this numerical methodology was extended to perform unit-cell calculations to investigate the void growth in porous ductile materials under monotonic loading conditions by prescribing constant triaxiality and Lode parameter throughout the loading. The simulations were carried out with random spatial distributions of pores and with void clusters. The calculations with random spatial distribution of voids revealed that the interaction between neighboring pores dictates the volume evolution of individual voids, especially at higher macroscopic triaxiality. The calculations with clusters demonstrated that pores clustering promotes localization/coalescence due to increased interaction between the voids, resulting in an increased growth rate of voids in clusters with large number of pores. Moreover, the results for the evolution of the distribution of plastic strains in the unit-cell have provided some quantitative indications of the role of porous microstructure on the development of heterogeneous plastic strain fields which promote macroscopic strain softening.en
dc.description.degreePrograma de Doctorado en Ingeniería Mecánica y de Organización Industrial por la Universidad Carlos III de Madrides
dc.description.responsabilityPresidente: Alain Molinari.- Secretario: Shmuel Osovski.- Vocal: Tore Børvik
dc.description.sponsorshipThe research leading to the results reported in this doctoral thesis has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme. Project PURPOSE, grant agreement 758056.en
dc.identifier.urihttps://hdl.handle.net/10016/43982
dc.language.isoengen
dc.relation.hasparthttps://doi.org/10.1016/j.ijplas.2021.103150
dc.relation.hasparthttps://doi.org/10.1016/j.ijsolstr.2022.111837
dc.relation.hasparthttps://doi.org/10.1016/j.ijplas.2023.103655
dc.relation.projectIDinfo:eu-repor/grantAgreement/ERC/H2020-EU.1.1./758056/EU/PURPOSE//
dc.rightsAttribution-NonCommercial-NoDerivatives 4.0 Internationalen
dc.rights.accessRightsopen accessen
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/
dc.subject.ecienciaMaterialeses
dc.subject.otherAdiabatic shear bandsen
dc.subject.otherCollapsing thick-walled cylinderen
dc.subject.otherDynamic torsionen
dc.subject.otherUnit-cell calculationsen
dc.subject.otherPorous microstructureen
dc.titleRole of porous microstructure on dynamic shear localization and ductile failureen
dc.typedoctoral thesisen
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