International Journal of Advanced Design and Manufacturing Technology
Volume:15 Issue: 2, Jun 2022

In this research work, sandwich composite panels made by fiber metal laminate (FML) as the facesheets and polymer foams as the core material are investigated in tensile and bending loads. To change or enhance the behaviour of sandwich panels in tensile and bending loads, shape memory alloy wires with pseudoelastic behaviour are also embedded in between FML layers in facesheets. The shape memory wires are also pre-strained in the FML facesheets of sandwich panels. To study the tensile and flexural properties of sandwich panels with smart FML facesheets three types of sandwich panels are considered and made including panels without shape memory alloy wire, panels with shape memory wires with 0% tensile pre-strain, and panels with shape memory wires with 5% tensile pre-strain for the same cross section. By placing SMA wires in the FML, the strength and stiffness of the smart sandwich specimens are increased significantly in tensile and bending loads. However, the effect of pre-straining the SMA wires is more predominant on stiffness of the specimens. The tensile and flexural toughness or energy absorption is much higher in case of the specimen with 5% pre-strained SMA wires. At the expenses of adding the SMA wires in the sandwich structures, the densities of various specimens are changed by nearly 1% to 5% for various specimens, but a significant increase in mechanical properties such as the strength and particularly the stiffness and toughness were achieved by the present lightweight smart sandwich structures.

This research aims to construct a three-dimensional numerical model for modeling friction stir extrusion using the completely Lagrangian method, smoothed particle hydrodynamics (SPH). For extrusion simulations, the Finite Element Method (FEM) is extensively utilized; however, it has limitations due to excessive element deformation. Because the particle-based method eliminates the usage of volumetric elements, SPH can be a viable alternative. The performance of the SPH model was evaluated using different particle sizes. The results showed that the smaller particle size improves the temperature results as well as the shape of the wire produced. Then the mechanical and microstructural properties of the produced wires were investigated. The results show that the grain size in the center of the wire is larger than its perimeter due to the lower strain rate in this area. Increased strain reduces grain size in the produced microstructure by increasing nucleation sites during recrystallization, as is well known. The wire microhardness in the centre is 121 HV, whereas it is 129 HV in the periphery. Grain size is the main reason of increased hardness near the sample's periphery.

A multi-layer controller of direct yaw moment for electric vehicles is developed in this study. In the upper layer, the yaw moment are obtained using Adaptive Sliding Mode Control (ASMC) with adaptation gain to track the desired vehicle yaw rate. The corrective yaw moments are applied by four in-wheel electric motors. The lower layer controller consists of a torque distribution algorithm and in-wheel motor torque controllers as well. The proposed torque distribution algorithm is intended to distribute the reference torques of each in-wheel motor controller appropriately based on both total longitudinal force and corrective yaw moment. To elucidate the effectiveness and robustness of the above control method, the simulation under various manoeuvres was carried out. A 7-DOF non-linear vehicle model is used for simulations and their results signify that the proposed control algorithm accomplishes a proper distribution of longitudinal force among four individual wheels, in turn, enhancing the yaw stability of the vehicle.

Environmental issues of hazardous metal wastes as well as growing demand for metals has increased focus on the forthcoming provision of metals. Therefore, the recovery and recycling processes of precious metals from secondary resources have become more prominent in the last years. Silver is one of the precious metals which can be recovered from wastes such as electronic wastes, coin and medal production losses, photographic films, and dental filling materials known as amalgam, which has the highest silver content. The present paper investigates the acid leaching of metals from a waste sample of dental silver alloy generated during the melt spray process. The alloy constitutes of 42.13% Ag, 31.03% Sn, and 26.84 Cu. The phase composition of amalgam generally consists of Ag2Hg3, Ag3Sn, SnxHg, Cu6Sn5, and Cu3Sn. The effects of the system temperature (25-80°C), nitric acid concentration as the leachate (13.75-65%), pulp density (33-200 g/l), and reaction time (0-240 min) on the dissolution recovery of silver, copper, and tin have been investigated. In the best case, we recovered 100% of silver and 98% of copper as soluble nitrates while tin was isolated as solid stannic oxide.

This article investigates the effect of magnetic field on the performance of a special shell-and-tube heat exchanger using ferro-nanofluid. The heat exchanger comprises seven twisted oval tubes with triangular array mounted on a hexagonal cross section. Water/iron oxide nanofluid with a volume ratio of 4% is used as hot fluid in tubes and water is employed as cooling fluid in the shell. The flow regime is laminar and calculations are performed at different Reynolds numbers and various magnetic fields. The governing equations include continuum, momentum, energy, and magnetic field equations that are solved using a finite volume method. It is demonstrated that the wall temperature of the tubes at the output is lower when the magnetic field is present compared to the case in which the magnetic field is not applied. Applying the magnetic field to the ferro-nanofluid leads to an increase in the Nusselt Number by about two times, leading to an increase in thermal efficiency of the heat exchanger. Also, the effect of the magnetic field was quite different with respect to the geometry and position of the tubes relative to the flow field. The effect of increasing the Nu in the first half of the twisting of the tube is approximately equal to the rate of reduction in the second half of the tube, resulting in a reduction in the impact of the magnetic field intensity.

Nowadays, disposable injection pumps are widely used in hospitals and home care settings to provide various therapies such as chemotherapy, antimicrobial, analgesic, and anesthetic treatments, as well as for postoperative pain control and chronic pain control. Since the accuracy of the injection is very important in infusion pumps based on the flow rate, it is therefore important to reduce the error in this device. In this study, the basic design principles of these pumps and the design problems of the sample appearance available in the market were investigated. Since one of the vital problems of this type of pump is their inaccuracy, because they are unable to inject a certain amount of drug for a certain period of time, so one of the main objectives of this study is to improve the accuracy of the injection. Also, as this device is available to the patient for a long time at the time of injection, ease of use is one of the design goals.  Finally, this paper ends with a design and prototype which is better in the shape of the device and a big improvement in the accuracy.

In the current research, interaction influences of obstacle shape and top wall velocity on the hydrothermal behaviours of the turbulent mixed convection flow in a trapezoidal cavity are numerically simulated. To achieve this goal, three different shapes of the obstacles including semicircular, triangular, rectangular are considered. Dimensions of these obstacles are chosen so that the environment around all three of them is same. The RNG  model is chosen to simulate the turbulent flow. To model the inclined or curved walls of trapezoidal cavity and obstacles, the improved blocked-off method is applied. Results show that the obstacle shape and top wall velocity have a significant influence on the thermal and hydrodynamic behaviours. In fact, the highest magnitude of heat transfer rate along the bottom wall occurs in the cavity with the rectangular obstacle and for the highest magnitude of top wall velocity; whilst its lowest magnitude is related to the pure free convection and for the cavity with the semicircular obstacle. Besides, the lowest and highest magnitudes of temperatures fields occur for the cavities with rectangular and triangular obstacles, respectively.

In this research study, an attempt is made to present a new optimization scheme by combination of the firefly algorithm and artificial bee colony (FA-ABC) to solve mathematical test functions and real-world problems as best as possible. In this regard, the main operators of the two meta-heuristic algorithms are employed and combined to utilize both advantages. The results are compared with those of five prominent well-known approaches on sixteen benchmark functions. Moreover, thermodynamic, economic and environmental modeling of a thermal power plant known as the CGAM problem is represented. The proposed FA-ABC algorithm is used to reduce the total cost and increase the efficiency of the system as shown in the Pareto front diagrams.

In this research, we investigate and compare the natural frequencies of simple beams and their mass and stiffness matrices of the two methods classic shape functions and real shape functions. To this end, we solve the beam motion Equation and apply boundary conditions. This article shows that the coefficients of the real shape functions, and consequently, the real shape functions, become harmonic and hyperbolic and also, they are dependent on the natural frequency value of the element. As a result, the real mass and the real stiffness matrix of each element are also dependent on the element frequency.  The frequency values obtained from these two methods are compared with the exact frequency values of two simple beam types with different support conditions. In this way, we determine which method leads to more accurate and acceptable frequencies for these beams. Based on the obtained results, the percentage of frequency error obtained by the classical method is relatively high in the sample beams. Hence, the natural frequency value of the beams studied using exact shape functions shows a small error compared to the classical method in terms of the exact frequency value of these beams. It is of note that the frequency error obtained from the classical method is greater in the elements with a higher natural frequency. Overall, obtaining the exact natural frequency of an element will result in accurate dynamic responses and more appropriate analyses and designs.

This paper presents a control system for elimination of chaotic behaviors in spur gear system. To this end, at first different aspects of chaos are investigated by means of numerical tools including time series response, phase plane trajectories, bifurcation diagram, Poincare’ section, Lyapunov exponent and power spectrum density. The nonlinear dynamic model encompasses constant mesh stiffness and damping along the line of action, static transmission error and backlash. In order to suppress the chaotic oscillations, a novel controller on the basis of the Predictive Sliding Mode Control (PSMC) is proposed in which the sliding surface is predicted by the use of model predictive control theory and the control input is obtained. Consequently, the control system takes advantage of the both approaches in developing a robust controller. The simulation results of the feedback system depict the effectiveness of the controller in elimination of the chaotic vibrations along with reduction of settling time, overshoots, and energy consumption. Furthermore, stability and robustness of the system are guaranteed.

The present paper examines thermal and hydrodynamic behavior of the incompressible laminar flow of a non-Newtonian magnetic nanofluid in a vertical rectangular channel numerically using two-phase mixture model, Carreau model, and finite volume method. The non-uniform transverse magnetic field is created by an electric current-carrying wire located along the channel. The Schiller-Naumann model is employed to calculate the slip velocity between the solid and liquid phases. The flow pattern and nanofluid temperature is assessed by changing effective parameters such as Reynolds number, the magnetic field strength, flow rate, mean axial temperature, and channel heat transfer. It is observed that the transverse secondary flow increases by increasing the magnetic strength due to Kelvin force. The hot fluid is transferred more from the sidewall to the center of the channel and the cold fluid moves from the center of the channel towards the wall, leading to an increase in heat transfer. Also, at low Reynolds numbers, more fluctuations occur in the velocity profile due to the dominance of Kelvin force over inertial force.