Dissertation/ Thesis
Porous materials: constitutive modeling and computational issues ; Πορώδη υλικά: καταστατική μοντελοποίηση και υπολογιστικά ζητήματα ; Modélisation théorique et numérique des matériaux poreux
| العنوان: | Porous materials: constitutive modeling and computational issues ; Πορώδη υλικά: καταστατική μοντελοποίηση και υπολογιστικά ζητήματα ; Modélisation théorique et numérique des matériaux poreux |
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| المؤلفون: | Xenos, Sokratis, Ξένος, Σωκράτης |
| بيانات النشر: | University of Thessaly (UTH) Πανεπιστήμιο Θεσσαλίας |
| سنة النشر: | 2024 |
| المجموعة: | National Archive of PhD Theses (National Documentation Centre Greece) |
| مصطلحات موضوعية: | Πορώδη μέταλλα, Θεωρία ομογενοποίησης, Μη-τοπικές θεωρίες, Μοντελοποίηση κατεργασιών διαμορφώσεως, Μοντελοποίηση όλκιμης θραύσης, Porous metals, Homogenization, Non-local theories, Forming simulations, Ductile fracture simulations, Métaux poreux, Homogénéisation, Théories non-locales, Simulations de formage, Simulations de rupture ductile, Επιστήμη Μηχανολόγου Μηχανικού, Επιστήμες Μηχανικού και Τεχνολογία, Μηχανολογία, Mechanical Engineering, Engineering and Technology, Mechanics |
| الوصف: | This work is concerned with the development, calibration, and numerical implementation of a novel fully explicit isotropic, rate-independent, elasto-plastic model for porous metallic materials. The microstructure is assumed to consist of a random, with uniform probability, distribution of randomly oriented spheroidal voids of the same shape. The proposed model is based on earlier homogenization estimates that use a Linear Comparison Composite (LCC) theory. The resulting expressions exhibit the simplicity of the well known Gurson model and, thus, their numerical implementation in a finite element code is straightforward. To assess the accuracy of the analytical model, we carry out detailed finite-strain, three-dimensional finite element (FE) simulations of representative volume elements (RVEs) with the corresponding microstructures. Proper parameter calibration of the model leads to fairly accurate agreement of the analytical predictions with the corresponding FE average stresses and porosity evolution. We show, both analytically and numerically, that the initial aspect ratio of the voids has a significant effect on the homogenized effective response of the porous material leading to extremely soft responses for flat oblate voids (e.g., aspect ratio less than 0.5) especially at high stress triaxialities. Next, we examine the computational issues related to the numerical implementation of rate-independent constitutive models that lead to softening behavior. It is shown analytically that elastic-plastic models based on "local" continuum formulations that do not incorporate a characteristic length scale may lead to loss of ellipticity of the governing partial differential equations (PDEs) and mesh-dependent numerical solutions. To remedy the associated numerical problems, we propose an implicit non-local version of the porous model developed in this work which is based on the introduction of a non-local porosity variable determined from the solution of an additional PDE. We show both analytically and numerically ... |
| نوع الوثيقة: | doctoral or postdoctoral thesis |
| اللغة: | English |
| Relation: | http://hdl.handle.net/10442/hedi/57170 |
| DOI: | 10.12681/eadd/57170 |
| الاتاحة: | http://hdl.handle.net/10442/hedi/57170 https://doi.org/10.12681/eadd/57170 |
| رقم الانضمام: | edsbas.6362F17F |
| قاعدة البيانات: | BASE |
| DOI: | 10.12681/eadd/57170 |
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