INTERNATIONAL JOURNAL OF ADVANCED DESIGN AND MANUFACTURING TECHNOLOGY
Year:2008 | Volume:1 | Issue:3 (3)|Papers Count:8

Composite pressure vessel CNG made of epoxy-carbon material with nonmetal liner is 60% lighter than aluminum vessel under the same conditions. One of the important parameters in the pressure vessels design is their resistance against impact and prevention of explosion. In this paper, the effects of low velocity impact on composite pressure vessel are investigated using FE analysis. The vessel reactions under velocity impact with different velocity, impact angle, and ply angle are studied based on Chang-Chang composite failure criterion. Finally, the effect of gas pressure inside the vessel before and after impact are analyzed.

Now a days, structures with planar geometry such as Sheet metals, have attracted special consideration among advanced techno logia, and hence investing vibration behavior of sheet metal is of prim important. In particular regarding dynamical investigations, if the natural frequencies get ignored, the resonance phenomena can exert noun computing damages to the structure and systems. In this research for investigating the plates' vibration behavior, finite difference method with error orders of O(h2) and O(h4) is implemented. t first, the classical and analytical solutions are reviewed and then relevant equations, needed for numerical analysis, are extracted for those mentioned error orders. Finally the obtained natural frequencies for both modes are compared non-dimensionally. In this research, finite difference method using error order O(h4), is being applied for the first time, however the reults of various references and simulation with ANSYS software are used to verify the outcome and accuracy of the proposed method.

At this study, after designing and manufacturing a rotary tool, its machining parameters and their effects on surface roughness of aluminum alloy of Al99 which is one of the most consumable alloys in aerospace industry, is studied and optimized. First, the rotary tool is designed and manufactred. Then according to Taguchi method, the experiments have been designed to record surface roughness, machining temperature and exerted forces on the tool. In order to evaluate optimum condition of the experiment results, MINITAB and Genetic Programming (GP) have been implemented to obtain the best regression; then for obtaining the optimum condition of machining, the results of running Genetic Programming has been used. In the end optimum machining parameters to achieve the best surface quality is presented.

In this research using statistical analysis the effect of machining parameters such as cutting velocity, feed rate, and tool type on machining power (Pm) in machining process of EN-AC 48000 aluminum alloy has been studied. A Taguchi L27 standard array has been utilized as the most economical array to evaluate the factors and their interaction. EN-AC 48000 alloy is frequently used in automotive and aerospace industry. Machining of this alloy is of vital importance because of generating the built-up edge and tool wear. Machining power is an essential factor affecting tool life, dimensional accuracy, and machining efficiency. Three types of cutting tools specialized for machining the aluminum alloys have been used for machining experiments. The effect of factors and their interactions have been studied; moreover, the optimum levels of factors have been offered. Finally, regression models to predict the machining power and related confirmation tests have been represented to evaluate the adequacy of equations.

For a long time, many efforts have been taken on improving gas turbine performance to increase the propulsive force and keep the chamber walls cool. In this regard, implementation of cyclonic and vortex engines have been proposed. According to increasing in the engine efficiency and keeping the chamber walls cool, the bidirectional vortex flow which is exited in the vortex engine, makes researchers more interested in it. In the vortex engine, due to its specific geometry, two vortex layers are established. The combustion occurs in the inner vortex layer, while the outer layer protects the walls from excessive heat transfer. The vortex engine with gas fuel and oxidizer has been manufactured in laboratory scale at Virginia Institute of Technology and it is under investigation. Practical usage of the vortex engine, with both liquid and solid fuels, has its own significance. Investigation and analysis of the flow field in such a chamber have been conducted in different research centers during last five years. The significant results of these studies are the analytical and numerical solution of the flow field by applying many simplifying assumptions. Selecting proper materials, determining the engine dimensions, designing injector plate, and some other parameters in engine manufacturing process require the flow field to be modeled in the combustion chamber which needs the governing equations to be solved. For investigating of the flow field in the vortex engine, the mass conservation, momentum conservation, and energy equations have to be solved. If the flow is turbulent, the equations become more complicated and many assumptions are needed to simplify the problem. Note that, by assuming the flow to be incompressible, the energy equation becomes segregated from the other equations. At the first stage, the goal of this project is to investigate the previous analytical solution and modify it to become compatible with other numerical and experimental results, provide numerical solution of the governing equations with the least possible assumptions, and compare the obtained numerical and analytical results with each other. Since the governing equations are non-linear and the flow is turbulent, it is impossible to solve the problem analytically in details. The flow will be simulated with respect to the result of numerical solution and applying the conventional methods and the results will be presented. It is to be noted that, if the fuel is liquid, modeling the spray combustion in a two-phase (gas-liquid) flow field is required, which will be described in this project as well. According to the flow field analysis, the propulsive and aero-dynamical results of the engine will be available, which are required to determine the designation parameters and manufacturing of the vortex engine test rig. Afterwards, by establishing the fundamental requirements for installing the appropriate test rig for the vortex engine, manufacturing of this test rig with its accessories will be described in details. The obtained results of this project, including the flow field investigation, test rig designation and implementation, are the first steps to achieve mass production of the vortex engine with both liquid and gas fuels which, according to its innovation and efficiency, has its own significance.

Unglazed transpired solar collectors are widely used for heating outside air directly, these days. Pre-heating ventilation air for large spaces and heating air for crop drying, are some of the applications of these kinds of collectors. The outside air is drawn straight from ambient, uniformly through the whole surface of a perforated absorber (transpired, dark-colored plate) exposed to the sun. That helps the air to be heated. Performance of these collectors is dependent on various parameters, such as geometry and type of perforations, suction velocity and the wind. In this study the role that wind (with constant direction and parallel to the plate) plays in performance of an unglazed transpired collector, is investigated by employing a commercial computational fluid dynamics code. In this study, plates are perforated with circular holes on either a square or triangular layout, covering the practical range of independent parameters such as, suction velocity, porosity, plate thickness, plate conductivity and wind velocity. Effectiveness, efficiency and pressure drop of these collectors are determined and the variations of these parameters with respect to variations of independent parameters are analyzed. It is shown that the performance of collectors on triangular layout, in similar conditions, is better than the same collector, on square layout.

Numerical analyses have shown that successful flow simulations and the accuracy of solution noticeably depend on the number of nodes used in computational meshing. A suitable meshing should have the capability of adapting with main flow parameters. Because the number of total nodes that can be used in numerical simulation is limited, making such grid for complex flows is almost difficult, if it is not impossible. Also, the regions of large solution gradients are not defined at the beginning. So using adaptive meshing in numerical solving methods is desired. Among adaptive meshing methods, adaptive-grid redistribution and embedding methods have been considered more by researchers. Combination of these two methods is more complex than each one alone. For the purpose of analyzing the accuracy and the efficiency of solution, the combination is used for solving two dimensional Euler equations in two model problems. The results show that using combination of adaptive-grid redistribution and embedding methods requires less nodes and therefore less memory and computation time. Therefore combination of this adaptive meshing is suitable.

In This Article, an unmanned airplane vehicle (UAV) has been design using a new method(Roskam method). This design is based on the maximum payload of 4kg, maximum altitude of 2500m, cruise speed of 120 km/h at sea level and loiter of 60 min. Based on this, desing configuration of the UAV with the aim of patrolling, recognition, and data aquzation, has been done, and design parameters including three-view of airplane is presented.