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  • Numerical Simulation of Particulate Erosion in a Single-Stage Turbine for Jet Engines
  • Abstract Recently, ceramic matrix composites (CMCs) are expected to utilize for the components of gas turbine engines due to its low density, high strength, and high rigidity in the high-temperature condition. The environmental barrier coating (EBC) is a key technology for the practical application of CMC to prevent surface regression from particulate and water vapor environments. However, the anti-erosion characteristics of CMC and EBC have not been clarified. In the present study, the authors performed numerical simulations of particulate erosion phenomena in a high-pressure turbine first stage to investigate the differences in the damage pattern and the performance between particle sizes.…
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  • Coupling VEM and BEM for computational homogenization of composite materials
  • Abstract The Virtual Element Method (VEM) [1] is a recent numerical technique that is capable of dealing with very general polygonal and polyhedral mesh elements, including irregular or non-convex ones. Because of this feature, the VEM ensures noticeable simplification in the data preparation stage of the analysis, especially for problems whose analysis domain features complex geometries, as in the case of computational micromechanics problems [2]. The Boundary Element Method (BEM) [3] is a well-known, extensively used and efficient numerical technique that has been successfully employed for the computational homogenization of materials with complex morphologies [4]. Due to its underlying formulation, the…
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  • Multiscale Topology Optimization using Subspace-based Model Reduction Method
  • Abstract High performance of the spacecraft structure is required in the special environment, it includes mechanical performance and operational performance, etc. When performing tasks, the spaceborne equipment requires high precision. Therefore, the design of lightweight, high stability and high reliability structure is essential for spacecraft. Topology optimization is widely used in structural design. However, there are some problems in the structure after macro topology optimization, such as checkerboard, local optimal solution and other phenomena. Despite a long calculation period, the obtained structure is often not smooth enough and hard to manufacture. Aiming to this issue, this paper proposes a combined method…
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  • The Analysis of Flexoelectric Effect in Quantum-Dot system
  • Abstract The flexoelectric effect is investigated in quantum dot (QD) nano-sized structures. The lattice mismatch between QD and matrix results in non-uniform strains and presence of the strain gradients in the structure. The strain gradients induces the change of the polarization in QD structure as a consequence of the flexoelectric effect. When the dimensions of the QDs are of the same order of magnitude as the material length scale, gradient elasticity theory should be used to account for the size dependent of such nano-sized QDs. In this work the flexoelectric theory is applied for 3D analysis of QDs with the functionally…
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  • Numerical Simulation of Glaze Ice Formation with Accompanied by Water Film Flow Using E-MPS Method
  • Abstract Icing is a phenomenon that super-cooled droplets impinge and accrete on a solid surface. When the icing occurs on aircraft wings, it deteriorates aerodynamic performances of the wings and the blade cascades of the engine, which may lead to severe accidents. Although number of investigations have been performed both experimentally and numerically [1], the icing shape prediction is now not practically complete due to the complex aspect of icing phenomena. In the previous research, Toba et al. [2] employed an explicitmoving particles simulation method (referred as E-MPS method), which was based on the Lagrangian approach, to reproduce the icing process…
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  • Global Analysis of Crisis in a Non-smooth Vibration Oscillator
  • Abstract Vibration isolation design is essential for the spacecraft capture operation in the on-orbit servicing missions. And contact impact is also inevitable in this process, which can be simplified as piece-smooth ordinary differential equations and generate abundant dynamics phenomena. Therefore, it is especially important to study the contact dynamics responses. And global behavior research can be visualized the characteristics of system. Aiming to this issue, the global dynamics of a single-degree-of-freedom non-smooth mechanical system in a vibration isolation experiment is studied by using advanced numerical procedure in this paper. For this non- smooth impact and friction oscillator, the forcing frequency is…
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  • A 3D multi-physics boundary element computational framework for polycrystalline materials micro-mechanics
  • Abstract A recently developed novel three-dimensional (3D) computational framework for the analysis of polycrystalline materials at the grain scale is described in this lecture. The framework is based on the employment of: i) 3D Laguerre-Voronoi tessellations for the representation of the micro-morphology of polycrystalline materials; ii) boundary integral equations for the representation of the mechanics of the individual grains; iii) suitable cohesive traction-separation laws for the representation of the multi-physics behavior of the interfaces (either inter-granular or trans-granular) within the aggregate, which are the seat of damage initiation and evolution processes, up to complete decohesion and failure. The lecture will describe…
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  • A Multigrid Coupled DEIM Method for High-Efficient Simulation of Compressible Gas Porous Flow
  • Abstract In natural gas engineering, the numerical simulation plays a significant role in the exploration, production and optimization of natural gas reservoir. However, numerical simulations of compressible gas flow in porous media are always expensive due to the gas compressibility and nonlinear properties. To save the computational cost, in this work we present a multigrid coupled discrete empirical interpolation method (MG-DEIM) to speedup the simulation of compressible gas porous flow. In this MG-DEIM framework, the core idea is that the multigrid method based on the full approximate scheme (FAS) is used to solve the flow equation (a pressure equation); for the…
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  • Basic concepts and numerical integration issues in the 2D boundary element implementation of strain gradient elasticity problems
  • Abstract The mathematical modeling of microdevices, in which structure and microstructure have approximately the same scale of magnitude, as well as of macrostructures of markedly granular or crystal nature (microcomposites), demands a nonlocal approach for strains and stresses. The present proposition is based on a simplified strain gradient theory laid down by Aifantis, which has also been applied mainly by Beskos and collaborators in the context of the boundary element method. This paper is an extension of a presentation made during the ICCES 2014 Conference in Crete, Greece, now relying on machine-precision evaluation of all singular and hypersingular integrals required in…
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  • Numerical Modeling of Material Deformation Responses Using Gradient Continuum Theory
  • Abstract In modeling of material deformation responses, the physical phenomena such as stress singularity problems, strain localization and modeling of size effects cannot be properly captured by means of classical continuum mechanics. Therefore, various regularization techniques have been developed to overcome these problems. In the case of gradient approach the implicit gradient formulations are usually used when dealing with softening. Although the structural responses are mesh objective, they suffer from spurious damage growth. Therefore, a new formulation based on the strain gradient continuum theory, which includes both strain gradients and their stress conjugates, has been proposed. In this way, a physically…
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