Vibration behavior of adaptive laminated composite beams integrated with magnetorheological (MR) fluid layer has been investigated using layerwise displacement theory. In most of the existing studies on the adaptive laminated beams with MR fluids, shear strain across the thickness of magnetorheological (MR) layer has been assumed a constant value, resulting in a constant shear stress in MR layer. However, due to the high shear deformation pattern inside MR layer, this assumption is not adequate to accurately describe the shear strain and stress in MR fluid layer. In this work a modified layerwise theory is employed to develop a Finite Element Model (FEM) formulation to simulate the laminated beams integrated with MR fluids. In the present model, each layer is modeled based on First-order Shear Deformation Theory (FSDT). The inter-laminar stresses between face-layer and MR layer is estimated more precise so FEM results are more accurate. Standard test of ASTM E 756-98 was employed to develop an empirical relationship for the complex shear modulus of MR fluid. Numerical examples have been illustrated the effects of MR fluid layer on the vibration behavior of the laminated beam. An experimental setup has been (FSDT) fabricated for the verification of the results.

The intricate 3D design of wind turbine blades has caused unwanted problems for blade designers and blade mold manufacturers. For example the cord length variation and twisting of airfoils, change of the airfoil type and the blade pre-bend can introduce major geometric complications. A novel method is suggested to improve 3D modeling of the blade mold surfaces as well as the required parting lines during the design process of the wind turbine blade. In the proposed algorithm, the blade leading edge surface is trimmed by parting lines calculated based on the blade silhouette while keeping G1 continuity of resulting surfaces. The Minimum Variation Surface (MVS) and strain energy fairing criteria approve that blade mold surfaces obtained by the developed method have better fairness compared to the surface created by the well-established design method. All programs are written in MATLAB and the final surfaces are converted into the standard IGES file format which is importable into any commercial CAD/CAM system.

EVA foams, like all other polymers, also exhibit strain-rate effects and hysteresis. However, currently available approaches for predicting the mechanical response of polymeric foam subjected to an arbitrarily imposed loading history and strain-rate effect are highly limited. Especially, the strain rates in the intermediate rate domain (between 100 and 102 s–1) are extremely difficult to study. The use of data generated through the drop tower technique for implementation in constitutive equations or numerical models has not been considered in past studies. In this study, an experiment including a quasi-static compression test and drop impact tests with a high speed camera was conducted. An inverse analysis technique combined with a finite element model for material parameter identification was developed to determine the stress–strain behavior of foam at different specific strain rates. It was used in this study to simulate multiple loading and unloading cycles on foam specimens, and the results were compared with experimental measurements.

An analytical solution is launched for Twin-cell Composite Box Beam (TCCBB) considering the impact of shear lag effects of concrete slab and twin-cell steel girder. To in-depth explore its mechanical mechanism, a new warping displacement mode of wide flange is chosen to meet the essential deformation feature of this TCCBB model by authors. Combining the virtual work principle with the thin-walled beam theory, its governing equations and boundary conditions are established for the TCCBB model. Closed form solutions for longitudinal strain and its shear lag coefficients are also derived under concentrated loads. What's more, experiment investigation and related parameter impact analysis are carried out for this established TCCBB model. Through this research, it shows that the proposed method can be applied to describe and predict shear lag behaviors for this type of composite structure. That further suggests that it provides a certain reference value for engineering design and its late reinforcement and maintenance in the composite structure.

In the present study, assuming that the thermo-elastic creep response of the material is governed by Norton's law, an analytical solution has been developed for the purpose of time-dependent creep response for isotropic thick-walled cylindrical pressure vessels. To study the creep response, the first-order shear deformation theory (FSDT) is applied. To the best of the researchers’ knowledge, in the literature, there is no study carried out into FSDT for time-dependent creep response of cylindrical pressure vessels. The novelty of the present work is that it seeks to investigate creep life of the vessels made of 304L austenitic stainless steel (304L SS) using Larson-Miller Parameter (LMP) based on FSDT. Using this analytical solution, stress rates are calculated followed by an iterative method using initial thermo-elastic stresses at zero time. When the stress rates are known, the stresses at any time are obtained and then using LMP, creep life of the vessels are investigated. The Problem is also solved, using the finite element method (FEM), the result of which are compared with those of the analytical solution and good agreement was found. It is found that the temperature gradient distribution has significant influence on the creep life of the cylinder, so that the maximum creep life is located at the outer surface of the cylinder where the minimum value of temperature is located.

In recent years, compact camera modules (CCMs) have been widely used in consumer electrical and electronic products. CCMs with low cost specially are necessary for portable devices. Therefore, the present group recently developed a miniaturized open-loop controlled camera module with low cost for cellphone applications, in which the Lorentz force is balanced by a magnetic restoring force. To enhance the performance of the camera module, this article reports a pattern structure to modify the linearity of the magnetic restoring force. We fabricated a CCM prototype with the dimensions of 8.5 mm × 8.5 mm × 5 mm and demonstrated the usefulness of the pattern structure with the CCM prototype. Its potential applications are foreseeable in portable devices, such as cellphones, web cameras, personal digital assistants and other commercial electronics.

This attempt addresses the peristaltic transport of Jeffrey fluid in a curved channel. Heat transfer is discussed employing convective condition at the channel walls. Effects of radial applied magnetic field and Joule heating are retained. Convective boundary conditions at both walls with different temperature are also accounted. The relevant equations are modeled in view of lubrication approach. Closed form expression for stream function is constructed. Numerical solution of stream function, velocity and temperature is obtained via shooting method in Mathematica with the help of NDSolve command. It is observed that curvature has opposite effects on the lower and upper walls of channel. However temperature is an increasing function of curvature parameter. Temperature also decreases in presence of heat transfer convective parameter naturally the Biot number.

The influence of temperature-dependent fluid properties on flow and heat transfer of an electrically conducting fluid over a stretching sheet with variable thickness in the presence of a transverse magnetic field is analyzed. Using similarity transformations, the governing coupled non-linear partial differential equations (momentum and energy equations) are transformed into a system of coupled non-linear ordinary differential equations and are solved numerically by Keller-box method. For increasing values of the wall thickness parameter, the analysis reveals quite interesting flow and heat transfer patterns. The effects of the temperature dependent viscosity, the wall velocity power index, the thermal conductivity, the wall temperature parameter and the Prandtl number on the flow and temperature fields are presented. The obtained numerical results are compared with the available results in the literature for some special cases and are found to be in excellent agreement. The skin friction and the wall temperature gradient are presented for different values of the physical parameters and the salient features are analyzed.

Speaking is a very complex process resulting from the interaction between the air flow along the larynx and the vibrating structure of the vocal folds. Sulcus is a disease missing layers in the vocal folds result in cracks resulting in some disorders in producing sounds. Sulcus and its effects on the vocal cord vibrations are numerically studied for the first time in this paper. An ideal model of healthy vocal folds and Sulcus vocalis has been two-dimensionally defined and the finite element model of vocal folds is solved in a fully coupled form. The proposed calculative model was used in a fluid range of the computational fluid dynamics, arbitrary Lagrangian-Eulerian (ALE), incompressible continuity and Navier-Stokes equations and in a structure range of a three-layer elastic linear model. Self-excited oscillations were presented for vocal folds among type II patients and compared with healthy models. Responses were qualitatively and quantitatively studied. The healthy model was compared with numerical and empirical results. In addition, the effects of the disease on the flow parameters and the vibration frequency of the vocal folds were studied. According to the simulated model, the oscillation frequency decreased 25% and the average and instantaneous volume flux significantly increased compared to healthy samples. Results may help present a guideline for surgery and subsequently evaluate patients’ improvement.

In this study, attention is focused on the numerical simulations of laminar fluid flow and heat transfer in straight smooth-walled parallelogram channels with various aspect ratios (α) and inclined angles (θ). The Reynolds number (Re), characterized by the channel hydraulic diameter and the working fluid of water, is fixed at 100. The examined α and θ range from 1 to 10 and 45° to 90°, respectively. Their effects on the thermal fluid features are explored under three thermal boundary conditions: constant wall temperature (TBC), constant axial heat transfer rate with constant peripheral temperature (H1BC), and constant wall heat flux (H2BC). The SIMPLE algorithm is employed for velocity–pressure coupling with the algebraic multigrid method, while the second-order upwind scheme is utilized for spatial discretization in pressure term; the momentum and energy equations are solved with a QUICK scheme; Least Squares Cell-Based Gradient Evaluation is applied for predicting scalar values at the cell faces and for computing secondary diffusion terms and velocity derivatives. One of the new findings is that there exists a critical value of θ = 70° below which the Nusselt number under H2BC increases with increasing α whereas beyond which the trend reverses, a result distinct from those computed with TBC and H1BC. Moreover, TBC is found to be a time-saving alternative to H1BC. Furthermore, both Nusselt numbers under the three thermal boundary conditions and friction factor times Re are successfully and compactly correlated with α and θ to offer useful reference for designing micro-cooling channels.

Louvered cavities are extensively employed in engineering applications. In the configurations of flow past these cavities, self-sustained oscillations will be excited. This can give rise to structure vibrations or noise. Numerical models are established to analyze excitation condition for of these oscillations. Computational results reveal that the excitation condition can be quantitatively described by the ratio of gap width G to the boundary layer thickness δ at the separation edge. When G/δ exceeds a certain critical value G/δc, self-sustained oscillations are excited. Otherwise, disturbances will dissipate and the flow configuration along the louver will be like a parallel plate flow. The critical value G/δc decreases with the ratio of G to the thickness of the louver plate H. This suggests that the excitation condition is more easily satisfied for a louver with sparse fins. The bottom boundary of the cavity restricts the feedback flow and then suppresses the excitation of self-sustained oscillations. With an increasing cavity height Hc, which reflects the distance between the louver and the bottom boundary, the critical value G/δc decreases and the decreasing rate reduces gradually. In contrast, because G/δc is relatively insensitive to the cavity length Lc, the side boundaries have no obvious influence on the excitation condition.

In the propagation of seismic waves through layered media, the boundaries play crucial role. The boundaries separating the different layers of the earth are irregular in nature and not perfectly plane. It is, therefore, necessary to take into account the corrugation of the boundaries while dealing with the problem of reflection and refraction of seismic waves. The present study explores the reflection and refraction phenomena of SH-waves at a corrugated interface between visco-elastic half-space and fibre-reinforced half-space. Method of approximation given by Rayleigh is adopted and the expressions for reflection and transmission coefficients are obtained in closed form for the first and second order approximation of the corrugation. The closed form formulae of these coefficients are presented for a corrugated interface of periodic shape (cosine law interface). It is found that these coefficients depend upon the amplitude of corrugation of the boundary, angle of incidence and frequency of the incident wave. Numerical computations for a particular type of corrugated interface are performed and a number of graphs are plotted. Some special cases are derived.

In this note, Föppl-Hencky membrane equation in the case of axisymmetric deformation was derived, and its power series solution was presented by using the displacement-based solution method. The result shows that both the displacement-based solution method and the stress-based solution method are effective for the solution to Föppl-Hencky equation. But in comparison with the latter, the former makes the solving process some more concise. In addition, some issues concerned were also discussed.