Ünker, F.; Çuvalcı, O.

In this paper, a symmetric gyro with coupling to the tip mass of a beam mounted on a vibrating base is considered. Taking advantage of the angular momentum of the rotating gyroscope, gyrostabilizer systems are expected to become more widely actualized as they provide an effective means of motion control with several significant advantages for various structures. This paper mainly focused on finding optimized stiffness and damping values that minimize the vibration responses with the derivation of the frequency equations of a special combined gyro-beam system. Correctness of the analytical results is verified by numerical simulations. The comparison with the results from the derivation of the corresponding frequency equations shows that the optimized stiffness and damping values are very accurate.

Ünker, F.; Çuvalci, O.

This paper deals with the investigation of optimum values of the stiffness and damping which connect two gyroscopic systems formed by two rotors mounted in gimbal assuming negligible masses for the spring, damper, and gimbal support. These coupled gyroscopes use two gyroscopic flywheels, spinning in opposing directions to have reverse precessions to eliminate the forces due to the torque existing in the torsional spring and the damper between gyroscopes. The system is mounted on a vertical cantilever with the purpose of studying the horizontal and vertical vibrations. The equation of motion of the compound system (gyro-beam system) is introduced and solved to find the response measured on the primary system. This is fundamental to design, in some way, the dynamic absorber or neutralizer. On the other hand, the effect of the angular velocities of the gyroscopes are studied, and it is shown that the angular velocity (spin velocity) of a gyroscope has a significant effect on the behavior of the dynamic motion. Correctness of the analytical results is verified by numerical simulations. The comparison with the results from the derivation of the corresponding frequency equations shows that the optimized stiffness and damping values are very accurate.

Ünker, F.; Kaplan, E.; Çuvalcı, O.

Computational fluid dynamics (CFD) is widely used in device design to determine gas flowpatterns and turbulence levels. CFD is also used to simulate particles and droplets, which aresubjected to various forces, turbulence and wall interactions. These studies can now beperformed routinely because of the availability of commercial software containing highquality turbulence and particle models. In order to understand how the gas is brought down towafer, it is necessary to have a knowledge of the gas flow behavior very early in t he designspiral of the Tantalum nitride - Atomic layer deposition ( TaN- ALD) chamber by undertakingparametric investigation of the interaction effect between gas flow and the funnel structure.This paper presents such a parametric investigation on a generic TaN- ALD chamber usingCFD. The results presented have been analyzed for a total of 11 different cases by varyingneck and nozzle angles for a process gas. The gas flow was mainly investigated for the nozzleangles of 4.5 , 9 , 12 and 20 and the film thi ckness results were compared with numericalflow patterns. CFD simulations using the turbulence model in ANSYS Fluent v.13 areundertaken. The parametric study has demonstrated that CFD is a powerful tool to study theproblem of gas flow structure interaction on funnel and is capable of providing a means ofvisualizing the path of the gas under different operating conditions .

Ünker, F.; Çuvalci, O.; Sener, S; Saridogan, E; Staub, S

This paper first points out the retaining higher order terms in the main equation of previous study (PS) of Friswell et al. (Journal of Intelligent Material Systems and Structures 23(13): 1505-1521, 2012). The equations of motion for the system are derived following energy (Lagrange) based approaches and the correct equation with the extra higher order terms is provided and simulations are redone in the current study (CS). (C) 2015 The Authors. Published by Elsevier Ltd.

Ünker, F.; Çuvalci, O.; Sener, S; Saridogan, E; Staub, S

In this paper, a system of the gyroscopes coupled via the massless torsional springs and the massless torsional dampers mounted on the tip mass of a column subjected to a vibrating base is considered. The coupled gyroscopes are assumed to have reverse angular speeds, and the rotations to eliminate the torques due to the springs and the dampers. Taking advantage of the angular momentum of the rotating gyroscope, gyrostabilizer systems are expected to become more widely actualized as they provide an effective means of motion control with several significant advantages for various structures. The non-linear motions of the gyro-column system and the equations of motion for the system are derived following energy (Lagrange) based approaches and examples provided. On the other hand, the effect of the angular velocities of the gyroscopes are studied, and it is shown that the angular velocity (spin velocity) of a gyroscope has a significant effect on the behavior of the dynamic motion. It is also shown how the dampers and springs due to the motion between the suporting gimbals influence the dynamic behavior of the column. (C) 2015 The Authors. Published by Elsevier Ltd.

Ünker, F.; Çuvalci, O.; Sener, S; Saridogan, E; Staub, S

Taking advantage of the angular momentum of the rotating gyroscope, gyrostabilizer systems are expected to become more widely actualized as they provide an effective means of motion control with several significant advantages for various structures. In this paper, a symmetric gyro with coupling to the tip mass of a column mounted on a vibrating base is considered. The non-linear motions of the gyro-column system and the equations of motion for the system are derived following energy (Lagrange) based approaches and examples provided. On the other hand, the effect of the angular velocity of the gyroscope is studied, and it is shown that the angular velocity (spin velocity) Omega of gyroscope has a significant effect on the behavior of the dynamic motion. It is also shown how the damper and spring due to the motion between the suporting gimbal and tip mass influence the dynamic behavior of the gyroscope. It was concluded that the numerical investigations of this combined system has not been investigated up to the present time. (C) 2015 The Authors. Published by Elsevier Ltd.

Ünker, F.; Çuvalci, O.; Sener, S; Saridogan, E; Staub, S

In this paper, the characteristics of a vibration control system utilizing a gyro and its effectiveness in the control of the motion subjected to a seismic ground motion acceleration were studied. Lambda gyro design was presented as a vibration absorber for reduction of the column vibration, which has a potential for application to towers, high-rise buildings and other structures. The non-linear motions of the gyro-column system and the equations of motion for the system are derived following energy (Lagrange) based approaches and examples provided. On the other hand, the effect of the angular velocity of the gyroscope is studied, and it is shown that the angular velocity (spin velocity) Omega of gyroscope has a significant effect on the behavior of the dynamic motion. It is also shown how the damper and spring due to the motion between the suporting gimbal and tip mass influence the dynamic behavior of the gyroscope. (C) 2015 The Authors. Published by Elsevier Ltd.