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  • Computing the Electric and Magnetic Green’s Functions in General Electrically Gyrotropic Media
  • Abstract A method for an approximate computation of the electric and magnetic Green’s functions for the time-harmonic Maxwell’s equations in the general electrically gyrotropic materials is proposed. This method is based on the Fourier transform meta-approach: the equations for electric and magnetic fields are written in terms of images of the Fourier transform with respect to space variables and as a result of it the linear algebraic systems for finding Fourier images of the columns of the Green’s functions are obtained. The explicit formulas for the solutions of the obtained systems have been found. Finally, elements of the Green’s functions are…
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  • Sensitivity of Dynamic Response of a Simply Supported Functionally Graded Magneto-electro-elastic Plate to its Elastic Parameters
  • Abstract Dynamic response sensitivity of a simply supported functionally graded magneto-electro-elastic plates have been studied by combining analytical method with finite element method. The functionally graded material parameters are assumed to obey exponential law in the thickness direction. A series solution of double trigonometric function agreed with the simply supported boundary condition is adopted in the plane of the plate and finite element method is used across the thickness of the plate. The finite element model is established based on energy variational principle. The coupled electromagnetic dynamic characteristics of a simply supported functionally graded magneto- electro-elastic plate are decided by its…
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  • Thermo-elastic Stresses in a Functional Graded Material Under Thermal Loading, Pure Bending and Thermo-mechanical Coupling
  • Abstract Analytical expressions have been derived for the through thickness stresses of a Functional graded materials (FGMs) thin plate subjected to thermal loading, pure bending and thermo-mechanical coupling, respectively. The structure is comprised of a metallic layer, a ceramic layer and a functional graded layer. Continuous gradation of the volume fraction in the FGM layer is modeled in the form of an "m" power polynomial of the coordinate axis in thickness direction of the plate. Numerical scheme of discretizing the continuous FGM layer with different graded distributions such as linear (m=1), quadratic (m=2) and square root (m=0.5) has been developed by…
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  • Measurement Techniques of Torsional Vibration in Rotating Shafts
  • Abstract The measurement of torsional vibration is a common practice in certain fields, such as the automotive industry, power generation, or large alternative engines. Similarly, functional analysis and diagnostic of other equipment, which are not traditionally measured, can benefit greatly from this type of measurement. This review discusses some techniques used in industry to measure torsional vibration, briefly describing the types of sensors used and the transduction procedures. Choosing the most appropriate technique in each case not only responds to economic reasons, but also to other conditions of the given equipment, such as its design, coupled machines or devices, functional status…
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  • Prediction of Fracture Parameters of High Strength and Ultra-High Strength Concrete Beams using Minimax Probability Machine Regression and Extreme Learning Machine
  • Abstract This paper deals with the development of models for prediction of facture parameters, namely, fracture energy and ultimate load of high strength and ultra high strength concrete based on Minimax Probability Machine Regression (MPMR) and Extreme Learning Machine (ELM). MPMR is developed based on Minimax Probability Machine Classification (MPMC). ELM is the modified version of Single Hidden Layer Feed Foreword Network (SLFN). MPMR and ELM has been used as regression techniques. Mathematical models have been developed in the form of relation between several input variables such as beam dimensions, water cement ratio, compressive strength, split tensile strength, notch depth, and…
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  • 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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