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Displaying 7471-7480 on page 748 of 7787. Per Page  
  • Modeling in Thermal Behavior of Charring Materials
  • Abstract Physical and mathematical models are the key to analyze thermal behavior of charring materials in the thermal protection system of reentry vehicles subjected to aerodynamic heating. To explore the thermal behavior of charring ablator, we developed and compared two models (pyrolysis interface model and pyrolysis layer model) with pyrolysis and surface recession. Taking AVCOAT composites as an example, its nonlinear thermal behavior, which are caused by temperature dependent thermal properties, moving interfaces and moving boundary, were simulated using the calculation codes written respectively on the basis of the pyrolysis layer model and the pyrolysis interface model. Numerical results indicate that…
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  • Wave Propagation in Functionally Graded Piezoelectric-piezomagnetic Rectangular Rings
  • Abstract The ring ultrasonic transducers are widely used in the ocean engineering and medical fields. This paper proposes a double orthogonal polynomial series approach to solve the wave propagation problem in a functionally graded piezoelectric-piezomagnetic (FGPP) ring with a rectangular cross-section. Through numerical comparison with the available reference results for a pure elastic homogeneous rectangular bar, the validity of the proposed approach is illustrated. The dispersion curves and displacement distributions of various FGPP rectangular bars are calculated to reveal their wave characteristics. The results can be used for the design and optimization of the ring FGPP transducers.
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  • Modeling of Hydro-Viscoelastic State of Deformable and Saturated Product During Convective Drying
  • Abstract A mathematical model was developed to simulate in 2D the spatiotemporal evolution of the moisture content, the temperature and the mechanical stress within a deformable and saturated product during convective drying. A comprehensive hydro-thermal model had been merged with a Maxwell model with two branches, assuming a viscoelastic material, a plane deformation and an isotropic hydric-shrinkage of the sample. A long sample of clay mixture with a square section was chosen as an application case. The transport and equilibrium properties of the product required for the modeling were determined from previous experiments which were independent of the drying trials. In…
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  • Sound Propagation Analysis on Sonic Crystal Elastic Structures using the Method of Fundamental Solutions (MFS)
  • Abstract The study of periodic structures, namely sonic crystals, for sound attenuation purposes has been a topic of intense research in the last years. Some efficient methods are available in literature to solve the problem of sound propagation in the presence of this kind of structures such as those based in the Multiple Scattering Theory (MST) or the Finite Element Method (FEM). In this paper a solution based on the Method of Fundamental Solutions (MFS) which presents advantages, namely in computational discretization and calculation costs, is presented. The proposed formulation considers the presence of elastic ring shaped scatterers, correctly accounting for…
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  • Magneto-Mechanical Finite Element Analysis of Single Crystalline Ni2MnGa Ferromagnetic Shape Memory Alloy
  • Abstract Based on an existing micromechanical constitutive model for Ni2MnGa ferromagnetic shape memory alloy single crystals, a three-dimensional quasi-static isothermal incremental constitutive model that is suitable for finite element analysis is derived by using Hamilton's variational principle. This equation sets up the coupling relation between the magnetic vector potential and the mechanical displacement. By using the incremental equation and ANSYS software, the mechanical behaviors of martensitic variant reorientation for Ni2MnGa single crystals are analyzed under magneto-mechanical coupling action. And the finite element results agree well with the experimental data. The methods used in the paper can well describe the mechanical behaviors…
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  • Exact Solutions of Finite Deformation for Everted Compressible Hyperelastic Cylindrical Tubes
  • Abstract The eversion problem for a class of compressible hyperelastic thinwalled cylindrical tubes is examined. The mathematical model is formulated as a second-order nonlinear ordinary differential equation based on the theory of nonlinear elasticity. The exact solution that describes the mechanism of the finite deformation of the everted cylindrical tube is obtained. Using numerical simulations, it is shown that the initial thickness of the tube plays a significant role in the eversion.
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  • Mechanical Analysis of 3D Composite Materials by Hybrid Boundary Node Method
  • Abstract In this paper, an improved multi-domain model based on the hybrid boundary node method (Hybrid BNM) is proposed for mechanical analysis of 3D composites. The Hybrid BNM is a boundary type meshless method which based on the modified variational principle and the Moving Least Squares (MLS) approximation. The improved multi-domain model can reduce the total degrees of freedom (DOFs) compared with the conventional multi-domain solver. It is very suitable for the inclusion-based composites, especially for the composites when the inclusions are solid and totally embedded in the matrix domain. Numerical examples are presented to verify the improved multi-domain model and…
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  • Statistical Second-order Two-scale Method for Nonstationary Coupled Conduction-Radiation Heat Transfer Problem of Random Porous Materials
  • Abstract This paper develops a novel statistical second-order two-scale (SSOTS) method to predict the heat transfer performances of three-dimensional (3D) porous materials with random distribution. Firstly, the mesoscopic configuration for the structure with random distribution is briefly characterized Secondly, the SSOTS formulas for calculating effective thermal conductivity parameters, temperature field and heat flux densities are derived by means of construction way. Then, the algorithm procedure based on the SSOTS method is described in details. Finally, numerical results for porous materials with varying probability distribution models are calculated by SSOTS algorithm, and compared with the data by finite element method (FEM) in…
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  • Modelling of Nanoscale Friction using Network Simulation Method
  • Abstract The field of nanotribology in the last decades was established through the introduction of Atomic Force/Friction Force Microscopes. However, our theoretical understanding of the individual processes involved in friction force microscopy is limited. This work designs a reliable and efficient model for the stickslip phenomenon, following the rules of network simulation. The model is able to manage different types of potential between the tip and the sample surface, allowing different kinds of sample material and microscope tip properties to be simulated with only minor changes in the code. The most analysed tribological materials in technical literature are simulated to test…
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