Applied Mechanics and Materials Vols. 110-116

Abstract: Flux-difference splitting procedure is developed for the hyperbolic part of the governing equations of turbulent reacting flow. As a primer computation of turbulent flame velocity in methanol mixtures for various turbulent kinetic energy is presented.

Abstract: Steel cylindrical tank is one of the most common forms of liquid storage vessels. In this study the Imperialist Competitive Algorithm (ICA) is used to find the optimum size of a ground based cylindrical liquid storage tank that is supported at both ends and the design considerations are stability and strength constraints. In this study total internal pressure and total special pressure are assumed as two types of load. The optimization procedure is formulated with the objective to minimize the mass of the tank due to the allowable capacity of cylindrical tank.

Abstract: This work devoted to an ellipsoidal head of pressure vessel under internal pressure load. The analysis is aimed at finding an optimum weight of ellipsoidal head of pressure vessel due to maximum working pressure that ensures its full charge with stresses by using imperialist competitive algorithm and genetic algorithm. In head of pressure vessel the region of its joint with the cylindrical shell is loaded with shear force and bending moments. The load causes high bending stresses in the region of the joint. Therefore, imperialist competitive algorithm was used here to find the optimum shape of a head with minimum weight and maximum working pressure which the shear force and the bending moment moved toward zero. Two different size ellipsoidal head examples are selected and studied. The imperialist competitive algorithm results are compared with the genetic algorithm results.

Abstract: This paper presents an approach to optimization of critical buckling temperature based on imperialist competitive algorithm (ICA) for functional graded plates (FGP) to non-uniform distributed temperature load. The objective is to maximize the critical temperature capacity of a functional graded plate. The third-order shear deformation theory is used in the mathematical formulation. The numerical results reveal that the imperialist competitive algorithm (ICA) can efficiently minimize critical buckling under non-linear temperature on the FG plates.

Abstract: Ducted-fan unmanned aerial vehicle (UAV) is very beneficial in many civil and military applications. It has a good operational flexibility similar to helicopter. Normally, the ducting of high speed spinning fan is done for several reasons; the duct produces lift, it provides higher static thrust when compared to a bare fan of the same diameter, substantial noise level from a spinning fan or rotor can be suppressed, and it increase the safety level for both of the system and the user. However, the main challenge is to understand the aerodynamic characteristic of this vehicle. In this paper, computational fluid dynamic (CFD) is used to study the airflow and aerodynamic characteristic on a new configuration of ducted-fan UAV.

Abstract: Magnetic Suspension Flywheel (MSFW) is regarded as a promising attitude control actuator for the ultra-precision and long life-span spacecraft. The output vibration of an operating MSFW is an important criterion to evaluate the system’s performance. Based on the dynamics model of rotor with the residual imbalances and the transfer functions of the controller, the restoring electromagnetic forces and torques for the suspension of the rotor is calculated. Then a testing rig was designed to measure the displacements, currents and vibration outputs of the MSFW. The vibrations of the basement caused by reactions of the restoring forces and torques are calculated. In the end, the displacements, currents and vibrations of the operating MSFW are measured to evaluate the performance of the MSFW.

Abstract: In this paper, the Gas Metal Arc Welding (GMAW) process is studied and temperature field is gained in this process. Thermal effects of Gas Metal Arc (GMA) and temperature field from it on workpiece (copper) and shielding gas type, is the main key of process optimization for GMAW. Energy source properties of GMA strongly depend on physical property of a shielding gas. In this paper, carbon dioxide (CO₂) was used as an alternative gas for its low cost. The basic energy source properties of CO₂ GMA were numerically predicted ignoring the oxidation of the electrodes. It was predicted that CO₂ GMA would have excellent energy source properties comparable to that of He, Ar GMA. The numerical results show the time-dependant distributions of arc pressure, current density, and heat transfer at the workpiece surface are different from presumed Gaussian distributions in previous models.

Abstract: A simple analytical model for oblique ballistic impact of projectiles into fabrics are presented. This model is extension of Chocron-Benloulo penetration model. Results are compared with experimental data. There is good agreement between analytical and experimental results.

Abstract: Surface roughness is important for evaluating the machined surface quality. In this work, an Artificial Neural Network (ANN) surface roughness prediction model was developed by coupling it with Response Surface Methodology (RSM). For this interpretation, advantages of statistical experimental design techniques, experimental measurements, and artificial neural network were exploited in an integrated manner. Cutting experiments were designed based on small centre composite design technique to develop a RSM model. The input cutting parameters were: cutting speed, feed, and axial depth of cut, and the output parameter was surface roughness. The predictive model was created using a feed-forward back-propagation neural network exploiting the experimental data. The network was trained with pairs of inputs/outputs datasets generated by end milling medium carbon steel with TiN coated carbide inserts. The model can be used for the analysis and prediction of the complex relationships between cutting conditions and surface roughness, in metal-cutting operations, with the ultimate goal of efficient production. The ANN model was verified with the optimized parameters predicted by a coupled genetic algorithm (GA) and RSM technique also developed by the authors.

Abstract: The exergy and exergoeconomic of the Qazvin steam power plant carried out here. In this paper the exergy destruction and efficiency of each component of this power plant is estimated. Since in every power plant there are different working loads and ambient temperature is varying during seasons, the effect of the load variations and the ambient temperature on the exergy analysis of power plant are calculated in order to obtain a good insight into this analysis. According the results, the boiler has the highest exergy destruction rate. The variation of the ambient temperature, is at the range 5ºc to 30ºc. Increasing the ambient temperature, the exergy destruction rate of all components increased. Increasing load of the power plant from 125 MW to 263 MW increases exergy efficiency of boiler and turbine. Then exergoeconomic analysis is done. The results show that the boiler has the highest cost of exergy destruction. Economic factors including the relative cost difference (r_k) and exergoeconomic factor (f_k), are calculated for each component. According to the results, the boiler, the low pressure turbine and the condenser of Qazvin power plant, are major exergy destructors respectively.