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The paper investigates the combined effect from the dendritic structure and grain orientation on the deformation behavior of the additively manufactured AlSi10Mg alloy. Micromechanical models comprising Al cells separated by a Si-rich eutectic network are constructed using the experimental data. The constitutive behavior of the Al phase is described in terms of the crystal plasticity to consider its crystallographic orientation. Intragranular stress and strain partitioning between Al and Si phases is analyzed numerically. The cellular dendritic structure is shown to be responsible for the anisotropy of mechanical properties of as-built Al-Si alloys.

This study develops a crystal plasticity-based model incorporating prismatic, basal, and first-order < c  +  a > pyramidal slip systems, as well as tensile twinning. A set of finite-element calculations is performed for the α‑titanium single crystal with tension applied along the [0001] axis. The results reveal that twinning is initiated in regions of high pyramidal slip and is accompanied by local lattice reorientation, enabling the activation of prismatic slip. The latter subsequently becomes the dominant deformation mechanism in the twin regions. The variation in the critical value of accumulated pyramidal slip is shown to affect twin propagation, emphasizing the need for careful calibration of the model parameters using experimental data.

Micromechanical simulations with an explicit account of the material microstructure provide valuable information on the microscale stress and strain distributions under loading. The construction of 3D microstructure models reproducing realistic microstructure morphology is a challenging task of computational mechanics and materials science. In this paper, a semi-analytical method of step-by-step packing to construct 3D microstructure models of polycrystalline and composite materials is presented. The main idea of the method is to pack a pre-meshed volume with 3D microstructure elements in a stepwise fashion in accordance with a set of geometrical-based algorithms specific for each type of the microstructure. The seed distributions and growth laws are the main parameters controlling the microstructural patterns. It is shown in particular examples that using different growth laws and seed distributions as well as their various combinations it is possible to construct 3D microstructure models with a wide variety of geometrical features. Some aspects of the numerical implementation not addressed before are given in detail.

The paper presents numerical simulation of polycrystalline titanium deformation in terms of the crystal plasticity theory. Based on the experimental data, a three-dimensional polycrystalline model is generated by a method of step-by-step packing. Constitutive relations for the deformation behavior of grains are based on the crystal plasticity theory with regard to the crystalline structure and dislocation glide in hexagonal closepacked crystal lattices. The boundary value problem of elastoplastic deformation is solved numerically using the finite element method. The proposed model is tested by elastoplastic deformation of titanium single crystals having different orientation. The proposed model is used to study the influence of the crystallographic orientation on localized plastic deformation in polycrystals.

Plastic strain localization and fracture in the nugget and thermo-mechanically affected zone of a friction stir welded Al6061-T6 alloy are numerically investigated. Dynamic boundary-value problems are solved by the finite-difference method. A procedure for generating ordered and disordered polycrystalline microstructures experimentally observed in different weld zones is developed. A physically-based relaxation constitutive equation is developed to describe dynamic thermomechanical response of the aluminum alloy. Calculations of microstructure tension in polycrystals are performed. The effect of the degree of order and strain rate on the material dynamic strength and fracture are studied.

A two dimensional cellular automata model has been developed to simulate and to study grain growth behavior during solidification and recrystallization processes, including predicting mechanical properties of metallic materials or investigating mechanical defects. Using the algorithm implemented, grain growth in model materials (nickel-based and titanium alloys) has been calculated in different thermal fields.

In this contribution, a mesomechanical approach to simulate the mechanical behavior with explicit consideration of the three-dimensional structure is applied to study the elasto-plastic response of a metal matrix composite material under tension. A procedure of a step-by-step packing (SSP) of a finite volume with structural elements has been used to design the composite structure consisting of an Al(6061)-matrix with Al2O3-inclusions. A three-dimensional mechanical problem of the structure behavior under tension has been solved numerically, using both an implicit finite-element method and an explicit finite-difference code. Special attention is given to the comparison of quasistatic and dynamic calculations. Evolution of plastic deformation in the matrix during tensile loading has been investigated. Qualitative and quantitative analysis of different components of stress and strain tensors is provided on the basis of mesomechanical concepts. Basing on the 3D-analysis, some conclusions regarding an applicability of a 2D approximation when considering deformation behavior on meso and macro scale levels have been done.

This paper presents a computational analysis of the deformation and fracture mechanisms of a material with a porous polysilazane coating under tension and compression. A dynamic boundary-value problem in the plane strain statement is solved numerically by the finite-difference method. The coating-substrate interface and porous coating microstructure corresponded to configurations found experimentally are accounted for explicitly in the calculations. For this purpose an algorithm for curvilinear finite-difference meshing based on the solution of the elasticity theory has been developed. The algorithm implemented offers several benefits over the rectilinear meshing. Local regions experiencing bulk tension are shown to form along pore surfaces that control the fracture mechanisms at the mesoscale level.

Numerical simulation of mechanical behavior of heterogeneous materials under loading with an explicit consideration for their 3D mesoscale structure is given. A 3-D problem in the dynamic formulation is solved using the finite-difference method. As an example, a coal specimen under tension and compression is examined, with an initial crack pattern taken into account. It is been shown that the fracture criterion we used in the calculations provides adequate description of fracture behavior under tension and compression on both macro and mesoscale level.