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This paper proposed a virtual testing method combining finite element procedure with heterogeneity weak bonding model to analyze the macroscopic responses of composite plates. Results show that wea...

A two-Dimensional Finite Element Method of electromagnetic (EM) wave propagation through the soil is presented in this chapter. The chapter employs a boundary value problem (BVP) to solve the Helmholtz time-harmonic electromagnetic model. An infinitely large dielectric object of an arbitrary cross-section is considered for scattering from a dielectric medium and illuminated by an incident wave. Since the domain extends to infinity, an artificial boundary, a perfectly matched layer (PML) is used to truncate the computational domain. The incident field, the scattered field, and the total field in terms of the z-component are expressed for the transverse magnetic (TM) and transverse electric (TE) modes. The radar cross-section (RCS), as a function of several other parameters, such as operating frequency, polarization, illumination angle, observation angle, geometry, and material properties of the medium, is computed to describe how a scatterer reflects an electromagnetic wave in a given direction. Simulation results obtained from MATLAB for the scattered field, the total field, and the radar cross-section are presented for three soil types – sand, loam, and clay.

A study on strategies regarding advancement in heat transfer characteristics in two-dimensional closed domains by placing cold cylinders is conducted. This effort is undertaken due to the fact that active and passive control in heat transmission is connected with provision of temperature differences at different locations of enclosures. Based on the experiments, researchers have concluded that placement of cold cylinder in non-uniformly distributed heat in a cavity is the most effective technique to enrich heat transfer rate, along with reducing the the waste of extra heat generation in processes such as polymer and aero dynamical extrusion, glass cooling, refrigeration, heating and cooling systems. Thus, the prime goal of this work is to outline heat and flow characteristics of non-linear fluid occupied in a square enclosure with adjustment of the cold cylinder. Heat transfer attributes are incorporated by accounting buoyancy forces and forming coupling of molecular diffusion of fluid within the flow domain. Formulation of the problem in dimensionless form is attained by encapsulating the aspects of natural convection in view of principal partial differential equations. Parametric study for governing expressions is computed numerically with the finite element method based on COMSOL Multiphysics version 5.6. Quadric interpolating functions are used to obtain information about velocity and temperature on nodes in elements. Hybrid meshing is manifested for discretization of the domain into rectangular and triangular elements. For the optimized variation in flow structures, prospective parameters are varied from 0.5≤n≤1.5, 5 ≤ Pr ≤ 35 and 102 ≤ Ra ≤106. The achieved results are projected graphically through streamlines, isotherms, and local and average Nusselt numbers. Tabular data for kinetic energy and wall heat flux are also calculated. It is inferred through the analysis that, with uplift in the Rayleigh number Ra elevation in the magnitude of kinetic energy and convective heat transfer arises, whereas the reverse pattern is depicted versus the power–law index n.

This paper is devoted to develop several cylindrical elements. The findings are used to solve Laplace’s equation numerically. It is sometimes required to solve this equation in the cylindrical coordinates. To take advantage from these situations, the suggested formulations are defined in a proper domain. Under this circumstance, it is superior that elements’ geometry is exactly modeled in the cylindrical coordinates. Consequently, no numerical integration scheme is required for performing these kinds of finite element procedure. In comparison to the classical finite element approach, the proposed formulas are able to solve the corresponding problem more accurately. To corroborate the robustness and efficiency of the suggested elements, several numerical samples are analyzed.

Finite element procedure is employed to analyze the free vibration characteristics of rotating functionally graded carbon nanotubes reinforced composite conical shell with pretwist under the thermal environment. In this paper, four types of carbon nanotube grading are considered, wherein the distribution of carbon nanotubes are made through the thickness direction of the conical shell. An eight-noded isoparametric shell element is used in the present formulation to model the panel based on the first-order shear deformation theory. For moderate rotational speeds, the generalized dynamic equilibrium equation is derived from Lagrange’s equation of motion, neglecting the Coriolis effect. The finite element code is developed to investigate the effect of twist angle, temperature, aspect ratio, and rotational speed on natural frequencies. The mode shapes of a carbon nanotube reinforced functionally graded conical shell at different twist angles and rotational speeds are also presented.

In this paper, we consider the solution of parabolic equations posted in domains with rough boundaries using the combined finite element procedure proposed in Xu et al. [A combined finite element m...

In this paper, a finite element simulation of nonlinear elasto-plastic deformations of Reissner-Mindlin bending plates is described. The previously proposed four-node Q4g element with transverse energy of shearing for thick bending plates is extended to account for isotropic material nonlinearities. An incremental finite element procedure has been used for the elasto-plastic analysis of the thick bending plate. Modified Newton-Raphson method has been used to solve the nonlinear equations. Von-Mises yield criteria have been applied for yielding of the materials along with the associated flow rule. To verify the present element, simple tests are demonstrated and various elasto-plastic problems in which the development of the plastic zone are solved.

In recent years, some unified critical state compatible (UCSC) frameworks have been established for constitutive modeling of both clean sand and sand with various quantities of fines. In existing UCSC frameworks, the equivalent granular void ratio e* and equivalent granular state parameter ψ* are used instead of the void ratio e and state parameter ψ to define the soil state and density state, respectively; this enables existing UCSC frameworks with the capability of constitutive modeling of sands with various quantities of non-plastic or low-plasticity fines using a unique set of model parameters. However, existing UCSC frameworks cannot be applied to cyclic loading. This study proposes a UCSC framework by merely substituting e* and ψ* for e and ψ into the equations of a stress-ratio controlled state-dependent plasticity model that includes cyclic loading simulation capabilities. The proposed UCSC framework is implemented in a fully coupled dynamic effective-stress finite element procedure. The simulative capability of the proposed UCSC framework is evaluated by comparison of the model predictions with existing experimental data of triaxial tests under monotonic and cyclic loading. Moreover, the effects of the fines content on the cyclic resistance ratio and the characterization of liquefaction susceptibility of sandy soils are investigated.

The hybrid formulation based on experimental data and the finite element procedure seems to be able to predict crack initiation under fatigue conditions for single lap joints aged by UV exposure. The UV exposure decreased stiffness and strength. The addition of graphene seems to postpone such ageing. However, by considering that cracks initiates when the (TS/σVM)~1. “Soft” adhesives can reach longer fatigue life at low loadings, while “stiff” adhesives have its fatigue life drastically decreased but at higher loadings. Stiff adhesives are more suitable for low cycle fatigue conditions, while for high cycle fatigue the option is a soft adhesive.

The term bioprosthesis is frequently employed to separate the purely mechanical valves from those with biologically originated leaflets. The bioprosthesis porcine valve is comprised of three tissue leaflets sutured onto a frame with three posts to support the leaflets. The leaflets are usually strengthened by immersion in a gluteraldehyde solution. Failure is dependent on the forces generated by the blood flow on the device, and is also dependent on the mechanical properties of the assembly. Dogbone shaped creep specimens of various grades of Dow polyacetal were prepared by injection molding with material flow along the length of the specimen from a single gate at one end of the specimen. The finite element method is the standard procedure for the analysis of complex structures. The finite element procedure was utilized to determine the deflection of the stent posts under static loading conditions as a function of time.

This paper presents in detail the two dimensional Finite Element Analysis of a Hybrid Excitation Synchronous motor. In particular, this document deeply analyses and describes the main FE analysis for an Hybrid Excitation Permanent Magnet motor. Motor alignment, no-load and on-load procedures are presented considering the conditions of Maximum Torque per Amps (MTPA) and Flux weakening (FW) working points.

Identifying the coupled system natural frequencies and dynamic behavior of systems in the presence of fluid-structure interaction is one of the most important issues in the engineering design of buildings, road vehicles and aircraft. This paper presents an efficient and flexible finite element procedure using fully vectorized codes for the free and forced vibration analysis of a rectangular plate in contact with fluid. The 4-node MITC plate finite element (MITC4) based on the Mindlin plate theory is used to simulate the plate, while the 8-node acoustic pressure element is used to simulate the fluid. The derived system of equations using structural displacements and fluid pressures yields a non-symmetric system of equations. Solving the generalized eigenvalue problem for the non-symmetric system is more computationally intensive compared to solving the generalized eigenvalue problem for symmetric systems. The modal expansion technique is used to reduce the model size. Then the reduced non-symmetric system is symmetrized by right eigenvectors. The Newmark method is used to solve the forced vibration problem of the coupled systems. The effect of the height of the fluid on the natural frequencies is discussed. The natural frequencies and transient responses are in good agreement with those obtained from the commercial finite element software. Moreover, the technique is proved to be effective to solve the coupled system.

In this paper, trajectory tracking control of suspended microchannel resonators (SMRs) is studied. A finite element procedure based on modified strain gradient theory will be used to model the SMR. Finite element methods usually lead to a model with a relatively high number of degrees of freedom. Thus, first, we will utilize the second order Krylov subspace method based on multi-moment matching to obtain a second order bilinear reduced system. Then, an output feedback controller and an optimal controller which take much less computation time and effort will be designed for the reduced system. The SMR is a micro-resonator which oscillates in a special frequency in practical cases, and thus tracking the desired paths is considered here as the control objective. Simulation results show the excellent performance of the proposed controllers.

During the lithiation and delithiation of a thin film electrode, stress in the electrode is deduced from the curvature change of the film using the Stoney equation. The accuracy of such a measurement is conditioned on the assumptions that (a) the mechanical properties of the electrode remain unchanged during lithiation and (b) small deformation holds. Here, we demonstrate that the change in elastic properties can influence the measurement of the stress in thin film electrodes. We consider the coupling between diffusion and deformation during lithiation and delithiation of thin film electrodes and implement the constitutive behavior in a finite-deformation finite element procedure. We demonstrate that both the variation in elastic properties in thin film electrodes and finite-deformation during lithiation and delithiation would challenge the applicability of the Stoney-equation for in-situ stress measurements of thin film electrodes.

In the paper, the shear performances of reinforced concrete beams strengthened with externally bonded SRG (Steel Reinforced Grout) composites were analyzed experimentally, analytically and numerically. The aims of this study were: i) to assess the experimental behavior of the SRG shear strengthened reinforced concrete beams by the evaluation of the influence of the main mechanical and geometrical parameters such as the strengthening configuration (continuous and discontinuous U-shaped SRG strips), the distance between the U-shaped SRG strips, the number of SRG layers and, the presence/absence of anchors; ii) to evaluate the effectiveness in predicting the shear capacity of strengthened beams of an analytical model found on a new formulation of the “effective strain” determined through the results of direct shear tests and, iii) to define a numerical model found on a finite element procedure developed through commercial software to predict the whole behavior of SRG strengthened beams. Nine reinforced concrete beams, one un-strengthened and eight strengthened in shear with U-shaped SRG (Steel Reinforced Grout) strips were tested. The experimental results evidenced that in comparison with the un-strengthened beams, the shear capacity: a) increased up to 80% and 53% in beams strengthened with continuous and discontinuous U-wraps, respectively; b) increased with the number of SRG layers (19% and 80% in beams strengthened by continuous U-shaped strips with one and two layers of SRG layers, respectively; 25% and 53% in beams strengthened with discontinuous U-shaped strips with one and two SRG layers, respectively); c) decreased with the distance between the U-shaped strips and, d) increased in average of the 90% in presence of the anchors. Experimental results, those described in this paper and others available in the literature, were used to evaluate the effectiveness of both the proposed analytical and numerical models. The obtained results allow evidencing that the analytical model furnishes predictions of the shear capacity of SRG strengthened beams in good agreement with the experimental results (the average value of the predicted/experimental ratio was 0.98). A very good estimation of both the ultimate loads and corresponding deflections of strengthened beams with negligible errors (less than 5%) whit respect to experimental results was, also, obtained by the numerical model.

Free vibration of coupled system including clamped-free thin circular plate with hole submerged in three-dimensional cylindrical container filled with inviscid, irrotational and compressible fluid is investigated in this work. Numerical approach based on the finite element method (FEM) is performed using the Comsol Multiphysics software, in order to analyze qualitatively the vibration characteristics of the plate. Plate modeling is based on Kirchhoff–Love plate theory. Velocity potential is deployed to describe the fluid motion since the small oscillations induced by the plate vibration is considered. Bernoulli’s equation together with potential theory is applied to get the fluid pressure on the free surface of the plate. To prove the reliability of the present numerical solution, a comparison is made with the results in the literature, which shows a very good agreement. Then, different parameters effect including fluid density, fluid height, free surface wave, hole radius and hole eccentricity on the natural frequencies of the coupled system is discussed in detail. Some three-dimensional mode shapes of the submerged plate are illustrated. Furthermore, the obtained results can serve as benchmark solutions for the vibration control, parameter identification and damage detection of plate.