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Hydraulic engine mounts are applied to the automotive applications to isolate the frame from the high frequency noise and vibration produced by the engine. It also designs to reduce the engine shake motions from the road distribution usually occurred at low frequencies. This implies that the stiffness and damping properties of the engine mount should be amplitude- and frequency- dependent. In the semi-active engine mounts this task will be done by changing the mount parameters such as stiffness and damping. Magneto-rheological fluids are used in the mounts to change their damping by applying the magnetic field. When the current is applied to the electromagnet and the magnetic field is present, the behavior of the magneto-rheological mount is changed by the magneto-rheological effects. In this paper, a prototype magneto-rheological mount was built and experimentally evaluated. Also, the mathematical model of the mount was developed to represent the dynamic behavior of the engine mount system. The model was numerically solved based on the prototype parameters and simulated in MATLAB. The experimental results were used to verify the model in predicting the mount characteristics.

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Hydraulic engine mounts are widely used in aerospace and automotive applications for vibration isolation. Here in this paper an active engine mounting system is proposed which not only acts like an isolator in a wide range of frequencies, but also performs as a damper when shock inputs and engine resonances are present. The proposed new design consists of a conventional passive fluid mount, an electromagnetic actuator (voice coil) and a capacitive circuit. The voice coil is placed in the lower chamber of the passive fluid mount and it can change the volumetric stiffness of the bottom chamber actively such that the mount has low dynamic stiffness in a wide range of frequencies. The capacitive circuit is paralleled with the voice coil and in situations when large shock inputs are present; it adds capacitance to the electromagnetic circuit and changes the characteristics of the mount from an isolator to a damper. Here in this paper the physical and mathematical models of the new mounting system are presented, the simulation results are shown and the performances of the proposed design in all active, passive and damper conditions are demonstrated.

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The chaotic behavior of a flexible rotor supported by active magnetic bearings is numerically investigated in this work. A statically unbalanced disk is mounted on the the shaft. The rotor is modeled by three lumped mass and 8 D.O.F. The rotor-AMB systems include many non-linear factors, such as nonlinear function of the coil current and the air gap between the rotor and the stator, nonlinearity due to geometric coupling of magnetic actuator, eddy current effect and hysteresis losses of the magnetic core material. In this work, the influence of weight parameter on nonlinear response of the system is investigated. Numerical results showed considering of weight parameter have important effect on the response of the rotor and exhibit a rich variety of nonlinear dynamical behavior including synchronous, sub-synchronous, quasi-periodic and chaotic vibrations. Bifurcation diagrams, phase planes, power spectra ,Poincar’e map and maximum lyapanov exponents are used to analyze the response of the system under different operational conditions. Chaotic vibrations should be avoided as they induce fluctuating stresses that may lead to premature failure of the machinery’s main component. It will be beneficial to the design of AMB system.

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Harvesting energy by piezoelectric materials is nowadays an efficient way for powering low-power electric devices. Required energy for sensors which are used in condition and health monitoring of bridges and other civil infrastructures can be examples of the energy harvesters. This study aimed to improve the piezoelectric-based energy harvesting on civil infrastructures, especially on bridge structures. In this investigation, harvesting energy from the vibrations of a bridge under moving consecutivemasses is studied. Harvesting energy iscarried out through a cantilever beam with piezoelectric patch which is installed atthe middle of a simply supported bridge. Governing equations for vibration of an Euler-Bernoulli beam under moving consecutivemasses arederived. The effects of inertial, centrifugal and coriolis forces areconsidered. For verifying, the results of the numerical solution of the moving mass problem are compared to the experimental tests data of the litterature. The harvester is modelled by a cantilever beam with piezoelectric patch under base excitations which are calculated from vibrations of the bridge mid-point. The obtained equations are then solved in MATLAB environment by using the forth order Runge-Kutta method. The calculated induced voltages are compared with those obtained from experiment. A good degree of accuracy is observed.

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This paper presents a completely practical control approach for quadrotor drone. Quadrotor is modelled using Euler-Newton equations. For stabilization and control of quadrotor a classic PID controller has been designed and implemented on the plant and a fuzzy controller is used to adjust the controller parameters. Considering that quadrotor is a nonlinear system, using classic controllers for the plant is not effective enough. Therefor using fuzzy system which is a nonlinear controller is effective for the nonlinear plant. According to the desire set point, fuzzy system adjusts the controller gain values to improve the performance of quadrotor and it leads to better results than classical PID controller. To study the performance of fuzzy PID controller on attitude control of the system, a quadrotor is installed to the designed stand. The system consists of accelerometer and gyroscope sensors and a microcontroller which is used to design fuzzy PID attitude controller for the quadrotor. Considering that the experimental data has lots of errors and noises, Kalman filter is used to reduce the noises. Finally using the Kalman filter leads to better estimation of the quadrotor angle position and the fuzzy PID controller performs the desired motions successfully.