INTERNATIONAL JOURNAL OF ADVANCED DESIGN AND MANUFACTURING TECHNOLOGY
Year:2008 | Volume:1 | Issue:4|Papers Count:8

Structures with planar geometries and analyzing their vibration behavior have attracted special and deep consideration these days. In this research for investigating the orthotropic plates' vibration behavior, finite difference method with error orders of O(h2) and O(h4) are implemented. At first, the classical and analytical solutions are surveyed 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. Also simulation with ANSYS software is performed for validation of the results and confirmation of the proposed method's accuracy.

In this paper, the effect of temperature difference between gas and particle in the structure of premixed flames propagation in combustible system, containing uniformly distributed volatile fuel particle, in an oxidizing gas mixture, is analyzed. In the present work, equations based on the premixed flames of organic dust are used and then required relations for gas and particle are derived. Consequently, governing equations and needed boundary conditions are applied and an analytical method is used for solving these equations. It must be said that the structure of the flame consists of a preheat zone, a reaction zone and a convection zone. Finally, the variation of dimensionless temperature of gas and particle, particle mass friction, equivalence ratio of gas and particle, flame temperature and burning velocity of gas and particle are shown in figures.

The present work attempts to characterize the flow of power-law fluids past a flat plate. However, since high viscosity (or equivalently low Reynolds number). Is often the case for non-Newtonian fluid flows, the errors resulting from applying boundary layer theory can be substantial and experimental or computational validation, which is often lacking, is particularly needed. This is part of the objective of the present paper. In this paper we consider a perpendicular grid, parallel to X and Y coordinate axis and to solve discretized form of the governing equations, control volume method and SIMPLE algorithm is compiled. Calculation have carried out writing a Visual Basic 6.0 language to test the reliability of the results comparisons are made with both Newtonian and fluent software in non-Newtonian case. It is found that at lower Reynolds numbers the boundary layer approximation is considered to be inadequate. All so the accuracy of boundary layers estimations are studied. The results show that by in creasing the power coefficient and fluid power the boundary layer size will increase and by decreasing them it will decrease.

In designing the landing gear of an airplane, one of the most important factors to consider, is the effect of landing airplane on body, and the role of shock absorber as an energy absorber resulting from landing. In this thesis, the landing gear of airplane has been analyzed using two approaches namely theoretical and simulation software. First, dynamic equations of landing airplane were investigated in six degrees of freedom and then, these equations were converted into space state and consequently solved using MATLAB software. In second approach, the airplane was modeled in ADAMS and different states of landing such as landing with two wheels, landing with three wheels, passing over a bump and taxi were compared and analyzed. Finally, using the above approaches velocity and displacement of airplane mass center were investigated, discussed and compared.

Successful development, evaluation, and qualification of propulsion systems such as turbojet and turbofan engines and rocket motors require the measurement of the performance and reliability of these systems. Thrust stands or testers are instruments for solid and liquid motors test. In this paper, a method for calculating of solid motors random vibrations effects on a thrust stand structure is developed. At first some Power Spectral Density (PSD) of three kinds of solid motors has been calculated by MATLAB codes. Then a typical thrust stand which has been designed based on special dynamics principles, has been modeled in Solidworks and transferred to ANSYS. In ANSYS, the structure has been analyzed modal and spectral. Then each motor's PSD has been applied on structure separately and maximum stress has been determined by ANSYS codes. Fallowed by structure fatigue life has been estimated by a formula derived from compound of Miner's cumulative fatigue damage ratio equation and Gaussian distribution curve. Results showed amount of PSD at first frequencies has more effect on structure fatigue life and just based on maximum motor thrust can not come to a definite conclusion about the vibrations effects.

In addition to increment of the vehicle sprung mass, the main physical effects of addition of CNG tank to the vehicle are the longitudinal and height displacement of center of gravity, which have the most influences on the handling, braking, roll stability and spin stability of the vehicle. Increment of CNG tank mass to the sprung mass of the vehicle increases the vehicle under-steer gradient, decreases roll stability and increases stability of vehicle on the straight line and S bends; meanwhile climbing ability of the front wheels drive vehicle is decreased. Due to increment of CNG tank to the sprung mass of the vehicle, the probability of vehicle spinout is increased, when driver brakes severely. First, we investigate the main components of vehicle dynamic performances which are affected by increment of CNG tank have been clarified. By using the available data and dominated equations on vehicle dynamic behavior, the vehicle performance has been analyzed.

Ultrasonic Assisted Drilling (USD) is new technique to drill difficult to machine materials. In this method, tool or workpiece vibrates with amplitude of few microns in addition to conventional drill bite rotation. In this experimental research, the bone was drilled both conventionally and using UAD, then the thrust was measured in two methods at feed rates of 50, 75 and 125 mm/s and 500, 710 and 1000 RPMs. The results show that USD method causes the thrust force decreases considerably in compare whit conventional drilling. The maximum temperature is less in USD at low RPMs.

An interface part is used between clutch pedal and clutch cable in Peugeot, Samand, RD and Peugeot pars. This part is consisted of two pieces. The Main body is made of polyamide 6.6 and the second part is made of CK45. Due to the fact that the two pieces are made of different assembling geometry with respect to each other, therefore, has caused performance problems which may result in clutch cable failure. Thus, a new interface part is designed in such a way that has a better assembling geometry and has overcome the previous problems and improved part functionality.