Micromechanical modeling of intrinsic and specimen size effects in microforming

Date

2018-09-01

Author

Yalçınkaya, Tuncay
Simonovski, I

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

190
views

0
downloads

Size effect is a crucial phenomenon in the microforming processes of metallic alloys involving only limited amount of grains. At this scale intrinsic size effect arises due to the size of the grains and the specimen/statistical size effect occurs due to the number of grains where the properties of individual grains become decisive on the mechanical behavior of the material. This paper deals with the micromechanical modeling of the size dependent plastic response of polycrystalline metallic materials at micron scale through a strain gradient crystal plasticity framework. The model is implemented into a Finite Element software as a coupled implicit user element subroutine where the plastic slip and displacement fields are taken as global variables. Uniaxial tensile tests are conducted for microstructures having different number of grains with random orientations in plane strain setting. The influence of the grain size and number on both local and macroscopic behavior of the material is investigated. The attention is focussed on the effect of the grain boundary conditions, deformation rate and the grain size on the mechanical behavior of micron sized specimens. The model is intrinsically capable of capturing both experimentally observed phenomena thanks to the incorporated internal length scale and the crystallographic orientation definition of each grain.

Subject Keywords

Strain gradient plasticity, Non-local plasticity, Crystal plasticity, Grain boundary, Size effect, Microforming

URI

https://hdl.handle.net/11511/37702

Journal

INTERNATIONAL JOURNAL OF MATERIAL FORMING

DOI

https://doi.org/10.1007/s12289-017-1390-3

Collections

Department of Aerospace Engineering, Article

Suggestions

OpenMETU
Core

Micromechanical Modelling of Size Effects in Microforming Yalçınkaya, Tuncay; SIMONOVSKI, IGOR; ÖZDEMİR, İZZET (2017-09-01) This paper deals with the micromechanical modelling of the size dependent mechanical response of polycrystalline metallic materials at micron scale through a strain gradient crystal plasticity framework. The model is implemented into a Finite Element software as a coupled implicit user element subroutine where the plastic slip and displacement fields are taken as global variables. Uniaxial tensile tests are conducted for microstructures having different number of grains with random orientations in plane str...
Three Dimensional Grain Boundary Modeling in Polycrystalline Plasticity Yalçınkaya, Tuncay; Firat, Ali Osman (2018-04-25) At grain scale, polycrystalline materials develop heterogeneous plastic deformation fields, localizations and stress concentrations due to variation of grain orientations, geometries and defects. Development of inter-granular stresses due to misorientation are crucial for a range of grain boundary (GB) related failure mechanisms, such as stress corrosion cracking (SCC) and fatigue cracking. Local crystal plasticity finite element modelling of polycrystalline metals at micron scale results in stress jumps at...
Plastic slip patterns through rate-independent and rate-dependent plasticity Lancioni, Giovanni; Yalçınkaya, Tuncay (2014-05-09) Plastic deformation induces various types of dislocation microstructures at different length scales, which eventually results in a heterogeneous deformation field in metallic materials. Development of such structures manifests themselves as macroscopic hardening/softening response and plastic anisotropy during strain path changes, which is often observed during forming processes. In this paper we present two different non-local plasticity models based on non-convex potentials to simulate the intrinsic rate-...
Micromechanical Modeling of Inter-Granular Localization, Damage and Fracture Yalçınkaya, Tuncay; Firat, Ali Osman; Tandogan, Izzet Tarik (Elsevier BV; 2018-08-31) The recent developments in the production of miniaturized devices increases the demand on micro-components where the thickness ranges from tens to hundreds of microns. Various challenges, such as size effect and stress concentrations at the grain boundaries, arise due to the deformation heterogeneity observed at grain scale. Various metallic alloys, e.g. aluminum, exhibit substantial localization and stress concentration at the grain boundaries. In this regard, inter-granular damage evolution, crack initiat...
Void growth based inter-granular ductile fracture in strain gradient polycrystalline plasticity Tandogan, I. T.; Yalçınkaya, Tuncay; Ozdemir, I (2021-12-01) The precipitation hardened, high strength aerospace alloys (e.g. Al 7000 alloy series) suffer from loss of fracture toughness due to the heat treatment leading to intergranular ductile fracture. Depending on the quenching and aging processes, large precipitates at the grain boundaries with wide precipitate free zones might develop. Therefore the grain boundaries constitute a potential location for micro void formation and evolution under the effect of external loads. This is a common problem of such materia...

Citation Formats

T. Yalçınkaya and I. Simonovski, “Micromechanical modeling of intrinsic and specimen size effects in microforming,” INTERNATIONAL JOURNAL OF MATERIAL FORMING, pp. 729–741, 2018, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/37702.