Micromechanical Modelling of Size Effects in Microforming

Yalçınkaya, Tuncay
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 strain setting. The influence of the grain size and number on both local and macroscopic behavior of the material is investigated. The model is capable of capturing both size effect due to statistical distribution of the grains and their size taking into account the grain boundary conditions. (c) 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the International Conference on the Technology of Plasticity.
Procedia Engineering


Strain gradient crystal plasticity: Intergranular microstructure formation
Özdemir, İzzet; Yalçınkaya, Tuncay (Springer International Publishing, 2016-01-01)
This chapter addresses the formation and evolution of inhomogeneous plastic deformation field between grains in polycrystalline metals by focusing on continuum scale modeling of dislocation-grain boundary interactions within a strain gradient crystal plasticity (SGCP) framework. Thermodynamically consistent extension of a particular strain gradient plasticity model, addressed previously (see also, e.g., Yalcinkaya et al, J Mech Phys Solids 59:1-17, 2011), is presented which incorporates the effect of grain ...
Intrinsic and Statistical Size Effects in Microforming
Yalçınkaya, Tuncay; Simonovski, Igor; ÖZDEMİR, İZZET (2017-04-28)
This paper analyzes the intrinsic (grain size dependent) and the statistical (grain number and orientation distribution dependent) size effects of micron level polycrystalline metallic specimens under plastic deformation through a strain gradient crystal plasticity framework. The macroscopic and local behavior of specimens from very limited number of grains to high number of grains are studied and the results are discussed in detail taking into account different boundary conditions.
Micromechanical modeling of intrinsic and specimen size effects in microforming
Yalçınkaya, Tuncay; Simonovski, I (2018-09-01)
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 micr...
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...
Micromechanical modeling of semicrystalline polymers with spherulite morphology
Oktay, Hasan Emre; Göktepe, Serdar; Gürses, Ercan; Department of Civil Engineering (2020-10-23)
In this study, a micromechanical constitutive model for semicrystalline polymers is developed. The proposed model considers interactions among the adjacent regions at the same length scale. The neighborhood information is obtained from the well characterized spherulite morphology of polyethylene. Deformation characteristics of a disk-like spherulite model that has similarities with the considered modeling approach are studied using the finite element method. The model discretizes a disklike spherulite i...
Citation Formats
T. Yalçınkaya, I. SIMONOVSKI, and İ. ÖZDEMİR, “Micromechanical Modelling of Size Effects in Microforming,” Procedia Engineering, pp. 998–103, 2017, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/37820.