Skip to Main content Skip to Navigation
Theses

Plasticité cristalline à gradients dans un cadre de grandes déformations pour modéliser les effets de taille dans les composants miniaturisés : Application à la localisation des déformations dans les tôles métalliques monocristallines et polycristallines

Abstract : Over the past few decades, the significant developments in micro-electronics and micro-electro-mechanical systems (MEMS) has led to a dramatically increasing demand for miniaturized products. The manufacture of these micro-scaled products is often a challenging task due to the presence of size effects, which render simple similarity-based rules for down-scaling conventional forming processes inapplicable. In micro-forming processes, size effects may influence both material and process parameters and must be carefully considered. When the geometrical dimensions of components down-scale from conventional (macroscopic) to microscopic level, the associated material behaviors become no longer size-independent. The influence of size effects on such behaviors has received a strong scientific interest in recent years and several works have been published on the subject. The present PhD work aims at corroborating these works by proposing a flexible numerical tool to model size effects within miniaturized poly-crystalline components.To model different kinds of poly-crystal size effects, the proposed numerical tool consists in a coupling between strain gradient crystal plasticity (SGCP) and grain boundary (GB) theories. As a part of this coupling, a flexible Gurtin-type model based on Gurtin (2007) approach was developed. A small deformation version of this model was first proposed to investigate the influence of the involved parameters on the prediction of size effects in the absence of large strain effects. A finite deformation extension was then proposed allowing for large strain applications. The implemented SGCP model allows for predicting first- and second-order effects within grains. To capture size effects due to grain boundaries, a finite deformation extension of the GB model proposed by Gurtin (2008) was performed within fully Lagrangian framewok accounting for plastic lattice distortion. Application of the SGCP and GB models to investigate size effects within poly-crystalline structures shows good qualitative reproduction of common experimentally observed size effects.As an application, the proposed numerical tool was applied to take a first step towards the modeling of size effects on the localization modes within single- and poly-crystalline structures. This numerical tool will be used in future to model size effects on the formability of ultra-thin sheet metals.
Complete list of metadata

https://pastel.archives-ouvertes.fr/tel-03686637
Contributor : ABES STAR :  Contact
Submitted on : Thursday, June 2, 2022 - 5:57:10 PM
Last modification on : Friday, August 5, 2022 - 2:54:00 PM
Long-term archiving on: : Saturday, September 3, 2022 - 8:06:30 PM

File

92418_CAI_2021_archivage.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-03686637, version 1

Citation

Lei Cai. Plasticité cristalline à gradients dans un cadre de grandes déformations pour modéliser les effets de taille dans les composants miniaturisés : Application à la localisation des déformations dans les tôles métalliques monocristallines et polycristallines. Mécanique des matériaux [physics.class-ph]. HESAM Université, 2021. Français. ⟨NNT : 2021HESAE066⟩. ⟨tel-03686637⟩

Share

Metrics

Record views

74

Files downloads

20