Aerospace Science and Technology
Enayatollah Hosseinian
Abstract
In this research designing the damper and control of system vibrations with the piezoelectric layers accommodation in studying the Flutter phenomenon will be considered. Accordingly, system structural modeling will be done in a continuous model of unmanned airplane wing. By considering all parameter ...
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In this research designing the damper and control of system vibrations with the piezoelectric layers accommodation in studying the Flutter phenomenon will be considered. Accordingly, system structural modeling will be done in a continuous model of unmanned airplane wing. By considering all parameter of the wing, the regions which have piezoelectric layers are modeled as beam with degree of torsion and bending freedom. Also, modeling the airflow behavior as quasi-steady will be done. By considering linear theory for piezoelectric structural equations, two layers will be bonded on the top and bottom of the beam. Due to design the damper and control of the vibration, Negative Feedback Control (NFC) algorithm will be used. To perform this algorithm, the lower piezoelectric layer acts as sensor. In fact, it has to measure the harvesting voltage. On the other hand, the upper piezoelectric layer, is the actuator of the system. In the other words, with feedback of measured voltage of the sensor to the controller, it applies new voltage to the system to control the stability of the system and at the end the flutter phenomenon can be postponed by using this algorithm. The results will presented for different values of feedback coefficient. Additionally, the effect of system main parameters on postponing flutter in each case of algorithm will investigated and optimized value of each parameter will showed based on postponing flutter phenomena.
Aerospace Science and Technology
Sajjad hajirezayi; Ali nouri; Enayatollah Hosseinian
Volume 12, Issue 2 , October 2019, , Pages 49-60
Abstract
Till now, various models have been proposed in literature to simulate the behavior of riveted structures. In order to find the most accurate analytical method in modeling the dynamic behavior of riveted structures, a comparison study is performed on several of these models, in this research. For this ...
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Till now, various models have been proposed in literature to simulate the behavior of riveted structures. In order to find the most accurate analytical method in modeling the dynamic behavior of riveted structures, a comparison study is performed on several of these models, in this research. For this purpose, experimental modal analysis tests are conducted on a riveted plate to verify the efficacy of the analytical models. Moreover, finite element model updating is used to reduce the difference between analytical and experimental results. First, the material properties of plates are optimized using the experimental results obtained from modal tests of a simple plate. Next, the optimization is performed for the physical properties of rivet. At the end, it is concluded that the fastener model proposed by Rutman can bring about the most accurate results when it is used in combination with solid plates and gap elements in the contact region.
Aerospace Science and Technology
Enayatollah Hosseinian; Ali Nouri; Majid Zia
Volume 12, Issue 1 , March 2019, , Pages 53-63
Abstract
In this paper, nonlinear vibration analysis of functionally graded piezoelectric (FGP) beam with porosities material is investigated based on the Timoshenko beam theory. Material properties of FG porous beam are described according to the rule of mixture which modified to approximate material properties ...
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In this paper, nonlinear vibration analysis of functionally graded piezoelectric (FGP) beam with porosities material is investigated based on the Timoshenko beam theory. Material properties of FG porous beam are described according to the rule of mixture which modified to approximate material properties with porosity phases. The Ritz method is used to obtain the governing equation which is then solved by a direct iterative method to determine the nonlinear vibration frequencies of FGP porous beam subjected to different boundary conditions. The effects of external electric voltage, material distribution profile, porosity volume fraction, slenderness ratios and boundary conditions on the nonlinear vibration characteristics of the FGP porous beam are discussed in detail. The results indicate that piezoelectric layers have significant effect on the nonlinear frequencies. Also it is found that the porosity has a considerable influence on the nonlinear frequency and these effects increased especially when the electric voltage is applied.
