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Journal bearing is one of the most important mechanical parts which can vastly be found in any application of mechanical camcorders such as engine, roterdynamic, aerodynamic and many more. One of the main performance related problems that this mechanical part may encounter during its service life is due to friction and wear over a short period of time, especially at high speeds, a one of the main challenges was to keep the shaft running efficiently for another hours. Many designs and modifications are attempted by researchers to improve certain specifications of the journal. In this construction a new design of the magazine bearing system was developed. It consists of three floors; the second is the bearing (internal and external) and the third is the thrust bearing. All three bearing units are combined into a single case as a magazine assembly. In this configuration, two hydrodynamic pressure profiles can be generated around the inner and outer fluid films in the circumferential direction and one in the axial direction. To predict the journal parameters, a mathematical model for the new magazine bearing design was developed using Reynolds' hydrodynamic equations. Lubrication in two dimensions. The governing partial differential equation was solved using Finite Difference method via MATLAB software. The main bearing parameters such as pressure, load capacity, friction force and so on are evaluated and their effect on journal geometry and operating conditions are investigated. A sample journal model was fabricated using CNC machine and tested experimentally with specially made testing rig, Vibration characteristics and stability of the journal are analyzed and studied also. The stress analysis of the journal housing are performed by using Finite Element method and excited by ANSYS 14. The effect of using Nano additive to the lubricant oil is studied both theoretically and experimentally. The preliminary results of this work indicated that the new suggested journal can significantly increase the ability of withstanding higher pressure and carrying load by about 23.60% and 12.90% respectively more than the traditional journal. Furthermore it exhibits less friction and higher critical operating speed. Using oil with Nano-particles can reduce friction by 16% with higher temperature operation. The optimum design conditions are occurred at 0.92 eccentricity ratio and 0.5 compound size ratio. [ABSTRACT FROM AUTHOR]

Researchers attempt to gain the benefit of any energy that can be produced from the structure of prosthetic legs. Such energy can be stored and released from elastic parts of the prosthesis like the foot, shank, and joints. The advantage is to reduce patient effort and consumption of metabolic energy. Unfortunately these prosthetic parts are mostly expensive and can not be manufactured locally by Prosthetics and Orthotics centres. The purpose of this study is to design a low-cost elastic shank that can be locally manufactured and can produce equivalent performance. In this work, four elastic shank models are suggested and designed using the SOLIDWORKS program. These models are; C- shape, S-shape, single circular shape, and double circular shape. Each model is analyzed using the finite element method to evaluate stresses, vertical deformation, and safety factors. Also, the stiffness for each model is calculated to investigate the amount of kinetic energy which can be stored in the shank and then can be released to assist the patient and reduce efforts. This energy can be used to improve a patient gait or reduce its metabolic energy. During the research spine, the main limitation was that there were a very low number of studies dealing with the topic of the research. It is found that; the lowest stiffness is found in the C-shape shank which means it is the most elastic design, in the same time it has the highest vertical elastic deformation at a maximum range that can be reached at 15 mm which is preferable when compare it to conventional shock absorber Pylon (shank) while the highest stiffness and lowest deformation at double circular shank which is not preferred for this application but it is the safest design due to reducing the stress concentration. Trade between safety and elasticity can be made to reveal that using of C shape is more optimal for designing elastic shanks. The value of this research is can be a base to manufacture a local elastic shank in Prosthetic and Orthotics centres and use it instead of using high-cost foot, shanks, and adapters [ABSTRACT FROM AUTHOR]

A new approach for evaluating the flutter instability boundaries based on the analytical solution of the equation of motion of cantilever pipes conveying fluid has been attempted. This approach leads to a simple transcendental equations form which the critical speed of flutter instability and the associated natural frequencies of cantilever pipes can be determined for any pipe parameters. The stability and critical natural frequencies maps can be simply constructed. The results of the presented approach are carefully checked with published results. The presented results showed very good agreements. [ABSTRACT FROM AUTHOR]

The dynamical behaviors of pipes containing pulsating fluids are nonlinear. In such nonlinear systems principal regions of dynamical instability can result from the effect of the periodic excitation of the fluctuated fluid flow. Evaluating the boundary frequencies for these types of instabilities had been carried out by many analytical and numerical methods. In this paper, an approximate "closed-form" solution for evaluating the principal boundary regions of instability for conservative pipes conveying pulsated fluid has been attempted. Bolotin's method was employed to split the boundaries from the stable regions. The resulting coupled-ordinary differential equations is decoupled by neglecting the effect of the mass ratio term and solved analytically. After imposing the specified boundary conditions, then the simplified formulas or transcendental equations were obtained for the pipes under consideration. These equations can give the principal boundary regions in term of the system parameters by simple calculations. The present solution was carefully checked with the "exact" solution where the mass ratio was included. The results showed good agreement for pinned-pinned clamped-pinned and clamped-clamped pipes conveying pulsating fluid. [ABSTRACT FROM AUTHOR]