Sharif Digital Repository

Magnetorheological (MR) materials indicate variations in their rheological properties when subjected to different magnetic fields. They have quick time response, in the order of milliseconds, and therefore are potentially applicable to structures and devices when a tunable system response is required. This study presents vibration analysis of laminated composite plate using MR fluid lumps under Random Excitation. A structural dynamic modeling approach is discussed and vibration characteristics of MR adaptive structures are predicted for different magnetic field levels. Linear Quadratic Regulator (LQR) controller is designed to achieve the vibration suppression of the laminated plate. The... 

Nowadays, the usage of probabilistic and reliability based frameworks is growing fast with respect to the development of computers. One of the most important issues which can be dealt in the field of structural/earthqauke engineering is the performance evaluation of the buildings equipped with active vibration control systems. In this research, in order to evaluate the performance of buildings probabilistically, the sampling simulation methods are applied. Accordingly, both structures and the loadings during their lifetime are considered as random variables. Therefore, at beginning, it is necessary to propose a model which is capable of producing structures with random properties. In this... 

Nowadays, applications of industrial robots are significantly increasing due to their flexibility, programmable, accuracy, rapidity and etc. Among these, machining robots play an important role at manufacturing industries. One of the main concerns of the researchers, is the tip vibrations of robot arms. In most times, these vibrations are self-excited, unpredictable and intolerable. Thus, finding a method for reducing vibration should be investigated. The purpose of vibration control is vibration suppression to enhance the reliability of the system. The aim of this project is the modeling of the machining robot arm in turning process and then application of robust control to reduce... 

As the aeronautical design evolves, the optimal solutions tend to employ slenderer and aeroelastic wings. These slender wings could help to increase the flight endurance, by decreasing the fuel consumption. However, as a wing becomes slenderer its structural stiffness decreases. The decrease in the stiffness highlights the structural vibrations and aeroelastic behavior in these wings. Atmospheric turbulences induce vibrations that can cause fatigue and structural failures. A possible solution to decrease these oscillations is to use active vibration control and flutter suppression. Conventional control surfaces on a wing can be used to implement the active vibration control. However, given... 

With the advent of new technologies in everyday human life, issues related to the use of vehicles have become crucial subjects of investigation. In this context, vibrations transmitted from the vehicle to the human body, especially in terms of long-term health effects, have garnered special attention and significance. The main objective of this research is to develop a control system for the active control of vibrations transmitted to the human body. To achieve this goal, a 5-DOF model of the human body has been employed as the study system. Considering the uncertainties in the parameters and dynamics of this model, H∞ and µ-synthesis methods have been utilized for robust control design. The...