INTERNATIONAL JOURNAL OF ADVANCED DESIGN AND MANUFACTURING TECHNOLOGY
Year:2013 | Volume:6 | Issue:4 (25)|Papers Count:12

In this paper, the amount of heat wasted from different parts of a 12-liter compression ignition engine and the recoverable heat from these parts were investigated. Then, two-stage configuration of organic Rankine cycle was introduced for simultaneous heat recovery from exhaust gases and coolant. Finally, parameters such as hybrid generated power, engine thermal efficiency, and brake specific fuel consumption were studied at different engine speeds under full engine load. By adopting this method, 35 kW hybrid power can be generated consequently, causing 9.5% reduction in brake specific fuel consumption.

Friction stir welding, a solid state innovative joining technique, is widely being used to join aluminium alloys for aerospace, marine automotive and many other applications of commercial importance. FSW trials were carried out using a vertical machining centre (VMC) on AA6061 alloy. The main objective of the present work was to evaluate the weld processing parameter of friction stir weld (FSW) process for AA6061-T6 alloy and to determine the properties of the obtained joints with respect of welding speed. Experiments have been conducted by varying the welding speed of 55-70 mm/ min and the rotating speed was fixed at 1700 rpm. Tensile properties, microstructure, microhardness, fractography, and corrosion resistance of FSW joints were investigated in this study. The result showed that there was a variation of grain size in each weld zone which depends upon the material and process parameters of FSW in the joint itself. The coarsest grain size was observed in heat affected zone (HAZ), followed by the thermomechanically affected zone (TMAZ) and the nugget zone (NZ). The maximum tensile strength of 184 MPa and highest joint efficiency of 49.32% were obtained on the joint fabricated at 55mm/ min of welding speed.

In this work, the influence of different EDM parameters (pulse current, pulse voltage, pulse on-time, pulse off-time) in finishing stage on the surface roughness (Ra) as a result of copper electrode application to a workpiece (cold work steel DIN1.2379) has been investigated. Design of the experiment was chosen as full factorial. Statistical analysis has been done and artificial neural network has been used to choose proper machining parameters in order to reach certain surface roughness. The experiment results indicated a good performance of the proposed method in optimization of such a complex and non-linear problems.

An elliptical tank cross-section is formulated to explore an optimization method, based on a real-coded genetic algorithm to enhance the roll stability limit of a tank vehicle. The genetic algorithm shape optimization problem is applied to minimize the overturning moment imposed on the vehicle due to CG height of the liquid load, and lateral acceleration and cargo load shift. The minimization process is performed under some major constraints such as cross-sectional area, overall height and width. The magnitudes of lateral and vertical translation of the cargo within the proposed optimal cross section under a constant lateral acceleration field are compared with those obtained with currently used elliptical cross-sections to demonstrate the performance potentials of the optimal shapes. The comparison of vehicle overturning moment revealed that the proposed optimal tank geometry is approximately 12% higher than the tank vehicle equipped with currently used elliptical and circular cross section tanks.

The integration of an approximate model and a clonal selection algorithm (CSA) is considered as one of the most effective ways to solve complex optimization design problems in engineering. In this study, first, a process for developing an approximate model and the principles of clonal selection algorithms is presented. Second, a variotherm temperature injection mold was used to produce a large liquid crystal display (LCD) TV panel. Next, an approximate model for optimizing the layout of the heating channels in the mold was established. Third, the clonal selection algorithm program was coded according to the aforementioned principles to solve the established approximate model. Finally, the layout of the heating channels was optimized and the optimal solutions were obtained. Finite element simulation and industrial injection production indicated that the integration of the approximate model and clone selection algorithm used in this study to optimize the layout of the heating channels for the injection mold was very effective.

The current study presents a new analytical method for buckling analysis of circular plates with constant thickness and Poisson’s ratio, made of functionally graded material subjected to radial loading. Governing equations are based on energy method for thin plates. The boundary conditions of the plate are assumed to be simply supported and clamped. The stability equations were obtained by using conservation of energy. The critical buckling load and first mode shape in terms of Bessel function of the first kind were obtained using Variational Calculus method. Increase in buckling capacity and improvement in the behavior of functionally graded plates in comparison to homogenous plates have been investigated.

Free vibration of simply supported circular cylindrical shell made of Functionally Graded Material (FGM) under internal pressure was investigated. The effective material properties are assumed to vary continuously along the thickness direction according to a volume fraction power law distribution. First order shear deformation theory based on Love's first approximation theory was utilized in the equilibrium equations. The effects of FGM parameters such as material configuration and power law exponent, internal pressure as well as geometrical parameters such as thickness to radius and length to radius ratios on the vibration behavior were investigated. The validation of the results was achieved by comparing with those available in the literature. The results show that the vibration characteristics of Functionally Graded (FG) shells are greatly influenced by FGM parameters. Moreover, internal pressure and geometrical parameters considerably influence the frequency behavior regarded to different values of FGM parameters.

Using piezoelectric patches, the stress concentration around a hole on a plate under tension is reduced and controlled. For this purpose, two placements for piezoelectric patches around the hole are investigated. First, the piezoelectric patches are located at top/ bottom of the hole with compression induced strain. This location controls the stress concentration directly. Then piezoelectric patches are located at left/ right of the hole with tension induced strains to control the stress flow in plate and reduce the stress concentration indirectly. The result sprung from the above conditions is presented for host plate and piezoelectric patches, and by comparing the mentioned results, the advantages of locating the piezoelectric patches to control the stress flow in the host plate is investigated. Based on the related results, locating piezoelectric patches at left/right of the hole can affect the stress flow around the hole and control the stress concentration factor indirectly.

This paper has focused on vibration and buckling of thin rectangular plates when at least two opposite sides are simply supported condition and subjected to axial and biaxial initial stresses. The relevant analysis is accomplished based on an exact solution method, free from any approximate method. First analytic techniques are used to discuss the free vibrations of plate. Then, natural frequencies and critical buckling loads are calculated. It is believed that through the present work, the exact closed-form characteristic equations and their associated eigenfunctions for the considered six cases are obtained for the first time.

In this paper, volume fraction optimization of Functionally Graded (FG) beams resting on elastic foundation for maximizing the first natural frequency is investigated. The two-constituent functionally graded beam consists of ceramic and metal. These constituents are graded through the beam thickness according to a generalized power-law distribution. One of the advantages of generalized powerlaw distribution is the ability of controlling the materials volume fraction of FG structures for considered applications. The primary optimization variables are the four parameters in the power-law distribution. Since the optimization processes are complicated and time consuming, a novel meta–heuristic called Imperialist Competitive Algorithm (ICA) and Artificial Neural Networks (ANNs) are implemented to improve the speed of optimization problem. The performance of ICA is evaluated in comparison with Genetic Algorithm (GA). Results show the success of combination of ANN and ICA for design of material profile of FG beam. Results also show that the combination of ANN and ICA can reduce the run time considerably.

Application of atomic force microscope as a manipulator for pushing-based positioning of nano-particles has been of considerable interest during recent years. However a detailed modelling of the interaction forces and control on the AFM tip is important for prosperous manipulation control, a reliable control of the AFM tip position during the AFM-based manipulation process is a main issue. The deflection of the AFM tip caused by manipulation force is the one of nonlinearities and uncertainties which causes difficulties in accurately controlling the tip position, the tip can jump over the target nano-particle then the process will fail. This study aims todesign a sliding mode controller (SMC) as robust chattering-free control in contact-mode to control the AFM tip during nano-manipulation process for accomplishment of a precise and effective nano-manipulation task in order to achieve the full automatic nano-manipulation system without direct intervention of an operator. The nano-probe is used to push the spherical micro/nano-particle. Nano-scale interaction forces, elastic deformation in contact areas, and friction forces in tip/nano-particle/substrate system are considered. The first control purpose is controlling and positioning the microcantilever tip at a desired trajectory by the control input force which can be exerted on the microcantilever in the Ydirection by a piezo actuator located in the base of the microcantilever. The second control target is PZT-driven positioning stage in AFM-based nanomanipulation in the X, Y in the flat surface. The simulation results show that the designed controllers have been able to make the desired variable state to track specified trajectory during a nano-scale manipulation.

In this study, thermo-mechanical nonlinear vibration of a polyethylene (PE) cylindrical shell embedded in an elastic foundation was investigated. The shell is reinforced by armchair Carbon nanotubes (CNTs) where characteristics of the equivalent composite being determined using Mori-Tanaka model. The elastic medium is simulated using the spring constant of the Winkler-type. The governing equations were obtained by employing nonlinear terms of strains-displacements based on Donell's theory, stress-strain relation, first order shear deformation theory and Hamilton's principal. Differential quadrature method (DQM) is used to calculate the nonlinear frequency of the shell. The influences of geometrical parameters, orientation angle of CNTs and elastic foundation constants on the nonlinear vibration of the shell were investigated. Results showed that the nonlinear effect represented by nonlinear frequency ratio is considerable at lower Kw.