The main objective of the present paper is to analyze the effects of phase-lag on thick circular plate with heat sources in modified couple stress thermoelastic medium. The mathematical formulation is prepared for three-phase-lag heat conduction model subjected to prescribed normal heat flux along with stress free boundary. Laplace and Hankel transforms are used to deal the problem. The displacements, stresses and temperature change are obtained in the transformed domain. Numerical inversion technique has been used to obtain the solutions in the physical domain. The results obtained numerically for these quantities are presented graphically. Some particular cases are also discussed in the present problem.

2-D graphene nanosheets (GNS) not only have superior mechanical properties, but stacking of GNS in composites is expected to inhibit moisture absorption. In this paper, moisture effect on tensile strength of graphene/epoxy nanocomposites is investigated. Two kinds of graphene reinforcements are used including graphene oxide (GO) and reduced graphene oxide (RGO) with reinforcement weight fraction WGO or WRGO in the range of 0.5 to 3.0wt%. A dispersion agent acetone is added in nanocomposites to enhance graphene dispersion. To evaluate moisture influence, those nanocomposites are soaked in two kinds of liquid including deionized water (DIW) and salt water (saline solution) for seven kinds of soaking periods of time including 24, 48, 72, 100, 400 hours, 30 days, and 60 days. After soaking test, diffusion coefficients of various composites are evaluated; besides tensile strengths of composites are measured by microforce testing machine. In order to correlate the strength with microstructure evolution, several techniques are adopted to analyze morphologies and functionalities of reinforcements and fracture surface of composites. They include Raman spectroscope, X-ray photoelectron spectroscope, and SEM. 2-D GNS are found to effectively enhance nanocomposites by moisture attack, and their corresponding reinforcing mechanisms are proposed.

In this paper, the effect of delamination on free vibration and primary resonance behaviors of composite circular plate with circular delamination is investigated. Through Reissner Variational Principle, the nonlinear dynamic equilibrium equations, the generalized displacements continuity conditions and the generalized forces equilibrium conditions across delamination front and consistent boundary conditions of delaminated circular plate are obtained. In the work, by introducing Bessel Function and Modified Bessel Function and using Galerkin discretization method, the nonlinear dynamic partial differential equations of delaminated circular plate are transferred into a set of nonlinear ordinary differential equations. Then by using semi-analytic method and multiple scales method, the effects of delamination radius and delamination depth in the thickness-wise on the natural frequency and primary resonance behaviors of delaminated circular plate are presented. The Results show that delamination has considerable effects on the natural frequency and its primary resonance behaviors of delaminated plate.

The present paper investigates the propagation of Love-type waves in an initially stressed heterogeneous fibre-reinforced layer with corrugated boundary surfaces, lying over a viscoelastic half-space under hydrostatic state of stress. The dispersion relation is obtained in closed form and found to be in well-agreement with the classical Love wave equation. The substantial effect of reinforcement, position and undulation parameters (i.e. corrugation), heterogeneity, horizontal initial stress and hydrostatic state of stress are discussed briefly. It is established through comparative study that reinforced layer supports more to phase velocity of Love-type wave as compare to reinforced free layer.

Depositing arch jamming of elliptical disks at the opening of a two-dimensional static hopper is studied experimentally. The hopper slope and opening width, and the aspect ratio of elliptical disks, are varied to determine their influence on the jamming probability. The jamming probability increases as the aspect ratio increases for gentle hopper slopes, while fluctuations of jamming probability appear for more steeper hopper slopes. Increasing hopper slope decreases the jamming probability in most cases. Most jamming arches result from the strong force chains along the shorter axes of elliptical disks. The disk number consisting of jamming arches decreases as the hopper slope increases. For smaller hopper openings, it decreases as the aspect ratio increases, whilst a nearly reverse tendency appears for elliptical disks with smaller aspect ratios. The study delivers a physical mechanism of jamming phenomena in depositing elliptical disks in a two- dimensional static hopper.

Through-Silicon-Via (TSV) is considered to be the most potential solution for 3D electronic packaging, and the mechanical properties of TSV-Cu are critical for TSV reliability improving. In this paper, to make deeply understand the creep behavior of TSV-Cu, nanoindentation creep tests were conducted to obtain its creep parameters. At first, the TSV specimens were fabricated by means of a typical TSV manufacturing process. Then a combination programmable procedure of the constant indentation strain rate method and the constant load method was employed to study the creep behavior of TSV-Cu. To understand the influence of the previous loading schemes, including the different values of the indentation strain and the maximum depths, the nanoindentation creep tests under different loading conditions were conducted. The values of creep strain rate sensitivity m were derived from the corresponding displacement-holding time curves, and the mean value of m finally determined was 0.0149. The value of m is considered no obvious correlation with the different indentation strain rates and the maximum depths by this method. Furthermore, the mechanism for the room temperature creep was also discussed, and the grain boundaries might play an significant role in this creep behavior.

This paper is to present the treatment of internal thermoelastic stress analysis in 3D anisotropic bodies by the boundary element method (BEM). Fundamentally, thermal effects will give rise to an additional volume integral in the boundary integral equation (BIE). By applying the fundamental solutions represented by Fourier series, the volume integral has been analytically transformed to the boundary. For the present work, spatial differentiations of the integral equation are performed to give displacement gradients at internal points of interest. This differentiated integral equation is further implemented to perform thermoelastic stress analysis inside 3D anisotropic bodies. This analysis is particularly important in engineering applications when thermoelastic stresses concentrations are present inside the bodies. The present work is the first BEM implementation for this study by the transformed BIE. In the end, two benchmark examples are tested to demonstrate the applicability of the present BEM treatment.

This survey examines the geometrically nonlinear bending of a doubly clamped nanobeam that is subjected to combined actions of actuator voltage, prestress, and intermolecular force, with the pull-in instability as the primary objective. A nonlocal Euler-Bernoulli beam model, which takes the small scale effect into account, is developed making use of the principle of virtual displacement on the basis of Eringen's nonlocal theory in conjunction with von Kármán assumption. Due to complexity of the resulting equations, a shooting technique is established through taking the applied voltage as an unknown and the central deflection as a control parameter. This treatment has the capability of tackling the nonlinearities from both the large deformation and electrostatic force as well as the intermolecular force and enables the size dependent deflection response to an applied voltage of the nanobeam to be obtained conveniently. Validation is conducted in numerical examples through direct comparisons with existing solutions to confirm the proposed method. Parametric studies are undertaken addressing the impacts of the nonlocal effect, intermolecular force, residual stress, and geometry of the beam on the pull-in behaviors.

This paper deals with entropy generation of two immiscible fluids inside an inclined channel under the influence of a uniform magnetic field. The channel consists of two regions such that a viscous fluid occupies the region I and an electrically conducting fluid occupies the region II. The governing equations of momentum and energy for two regions are solved by Mathematica package BVPh 2.0 which is based on homotopy analysis method. The analytical results are validated against other numerical simulations and experimental data and excellent agreements are achieved. The entropy generation components due to heat transfer and fluid friction for two immiscible fluids are formulated and then the total entropy generation is computed. The influence of various parameters including Grashof number, Hartmann number and inclination angle on the total entropy generation and its components is examined and discussed. Results show that total entropy generation has a direct relationship with Grashof number and inclination angle, while it has a reverse relationship with Hartmann number. It can also be found that although the enlargement of Hartmann number increases the contribution of entropy generation due to Ohmic dissipation, it still reduces the total entropy generation inside the channel.

A theoretical study is presented for the problem of orthogonal axisymmetric stagnation flow towards an infinite horizontal plate with a constant velocity in the presence of viscous dissipation and heat generation. The governing equations are reduced to a system of nonlinear ordinary differential equations by means of appropriate transformations for the velocity components and temperature. The similarity equations are solved numerically using the Matlab routine bvp4c. The results are compared with those known from the literature and an excellent agreement is found. The effects of involved parameters on the x-wise velocity component, temperature, skin friction, heat transfer and entropy generation rate are presented in graphical and tabular forms. It was found that the Eckert number Ec, the Prandtl number Pr and the heat generation parameter α play a significant role on the temperature, heat transfer and entropy generation rate.

A mathematical model has been developed to determine the best geometry of a compact heat exchanger in this research study. Accordingly, an objective function was introduced to define the optimized structure of the exchanger. Two main targets were pursued in this regard. First was the rate of existing discrepancy between the possible heat transfer rate in the exchanger and the maximum rate. Second was possible heat transfer consideration between exchanging gasses and incoming air of the furnace. A sample shell and tube heat exchanger of existing tube in a processing industry has been studied and the calculations have been performed to solve the relevant equations. In addition, a comprehensive code to design an optimized compact heat exchanger for heat recovery of the furnaces has been presented. Then, data gathering and model synchronization caused to a preliminary evaluation of model quality. Thus, for increasing accuracy level of mentioned research, along with measurements’ correction program, model modification has been done and new results were calculated. Optimization model analysis showed that by using this approach, not only significant heat conservation can be achieved, but also suggested procedure might be completely economical.

This paper deals with studying fluid flow and heat transfer of nanofluid through a forward facing step channel which is affected by a uniform magnetic field transverse to fluid flow. All the channel walls are assumed to be in constant temperature and the fluid temperature at the channel inlet is less than that of the walls. Also, the nanofluid is considered as a single-phase Newtonian fluid and the proper correlations were utilized to determine the thermophysical properties of nanofluid. Therefore, a code has been developed and two-dimensional continuity, momentum and energy equations were solved, using CFD technique. The computations were conducted for different values of the Reynolds and Hartmann numbers, and contraction ratio and an extensive range of nanoparticles volume fraction. The results indicated that flow separation and reattachment phenomena, in vicinity of the step edge, could be influenced strongly by magnetic field and the average Nusselt number is increased significantly by increasing nanoparticles volume fraction and Hartmann number.