Numerical Computation of Material Properties of Nanocrystalline Materials Utilizing Three-Dimensional Voronoi Models

Abstract

Nanocrystalline metals have been the cause of substantial intrigue over the past two decades due to their high strength, which is highly sensitive to their microstructure. The aim of the present project is to develop a finite element two-phase model that is able to predict the elastic moduli and the yield strength of nanostructured material as functions of their microstructure. The numerical methodology uses representative volume elements (RVEs) in which the material microstructure, i.e., the grains and grain boundaries, is presented utilizing the three-dimensional (3D) Voronoi algorithm. The implementation of the 3D Voronoi particles was performed on the nanostructure investigation of ultrafine materials by SEM and TEM. Proper material properties for the grain interiors (GI) and grain boundaries (GB) were computed using the Hall-Petch equation and a dislocation-based analytical approach, respectively. The numerical outcomes show that the Young’s Modulus of nanostructured copper increased by increasing the crystallite volume fraction, while the yield strength increased by decreasing the grain size. The numerical predictions were strongly confirmed in opposition to finite element outcomes, experimental results from the open literature, and predictions from the rule of mixtures and the Mori-Tanaka analytical models.

Mechanical Characterization of Nanocrystalline Materials via a Finite Element Nanoindentation Model

“…The analysis' objective is focused on the development of a numerical procedure via the parametric interaction representing the geometrical characteristics of nanostructured metals. The presumptions and the extensive numerical methodology used in the present work are described extensively in [48,65], on account of the completeness of the paper. The nanocrystalline materials are heterogeneous materials due to their discrete areas showing different physico-chemical and mechanical properties at the microscale level.…”

“…The nanocrystalline materials are heterogeneous materials due to their discrete areas showing different physico-chemical and mechanical properties at the microscale level. Based on this paradox, the mechanical response, taken by the proposed numerical methodology shown in [48,65], is the homogenized average medium of the equivalent heterogenous nanocrystalline material. More specifically, in [48,65], the presumptions were applied for the investigation of mechanical behavior of a fully dense, nanocrystalline material under uniaxial compressive loading, so as to extract the stress-strain response of an equivalent homogenized material from the heterogenous RVE (see Figure 4) at the nanoscale level under As it is commonly known, RVE is the smallest numerical volume for any material in which a macro-mechanical property can be defined through a multi-scale modelling approach.…”

Modelling and Experimental Validation of the Porosity Effect on the Behaviour of Nano-Crystalline Materials

“…The basic characteristics and the numerical methodology used in the present work are described detail in Reference [24]. In Reference [24], the numerical model was applied for the simulation of the behaviour of a full dense nanocrystalline material without taking into account the presence of any defect. In the present publication, the numerical methodology was extended so as to account for the presence of pores.…”

Failure Mechanisms in Alloys

“…More specifically, the broad category of static overload includes more generic subjects also from the field of manufacturing-related topics, where the effect of deformation and fracture was studied as an important and undetached ingredient of the fabrication process per se (e.g., hot and cold working, machining). Therefore, the mostly "intense area" (Overload/Static) comprises studies concerning general deformation and fracture phenomena, as the result of instant loading/testing conditions [4,9,10,14,15,19] and studies related to manufacturing and production processes [6,7,12,13,16,20,22,25,26]. Testing and modeling procedures addressing the evolution of deformation and fracture during forming [7,13,26], the impact toughness, [4] and certain production process characteristics [25] are also included.…”

“…Phenomenological and Experimental [1][2][3][4][5][6][7][8][9][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] 2. Numerical Modeling [6,7,10,12,13,15,25,26] 3. Statistical and Stochastic [8,16,20,22,25] 4.…”