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Applied and Computational Mechanics - Volume:1 Issue: 1, Winter 2015

Journal of Applied and Computational Mechanics
Volume:1 Issue: 1, Winter 2015

  • تاریخ انتشار: 1393/12/25
  • تعداد عناوین: 6
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  • Hamid M. Sedighi *, Farhang Daneshmand Pages 1-9
    This paper presents the high order frequency-amplitude relationship for nonlinear transversely vibrating beams with odd and even nonlinearities, using Homotopy Perturbation Method with an auxiliary term (HPMAT). The governing equations of vibrating buckled beam, beam carrying an intermediate lumped mass, and quintic nonlinear beam are investigated to exhibit the reliability and ability of the proposed asymptotic approach. It is demonstrated that two terms in series expansions are sufficient to obtain a highly accurate periodic solutions. The integrity of the analytical solutions is verified by numerical results.
    Keywords: Homotopy Perturbation Method with an auxiliary term, Non, linear vibrating beams, Frequency, amplitude relationship
  • Javad Meshkatifar *, Mohsen Esfahanian Pages 10-16
    In this paper, the effects of roll center height of McPherson suspension mechanism on dynamic behaviour of a vehicle are first studied, and then the optimum location of roll center of this suspension system is determined for a conceptual Class A vehicle. ADAMS/Car software was used for the analysis of vehicle dynamic behaviour in different positions of suspension roll center. Next, optimization process has been done using ADAMS/Insight. Results show significant effects of roll center location on body roll angle, body roll rate and steering response. Also, the contradiction between body roll and steering response can be observed.
    Keywords: Vehicle dynamics, Roll center height, McPherson suspension mechanism
  • Jamal Zare * Pages 17-25
    The present research attempts to explain dynamic pull-in instability of functionally graded micro-cantilevers actuated by step DC voltage while the fringing-field effect is taken into account in the vibrational equation of motion. By employing modern asymptotic approach namely Homotopy Perturbation Method with an auxiliary term, high-order frequency-amplitude relation is obtained, then the influences of material properties and actuation voltage on dynamic pull-in behavior are investigated. It is demonstrated that the auxiliary term in the homotopy perturbation method is extremely effective for higher order approximation and two terms in series expansions are sufficient to produce an acceptable solution. The strength of this analytical procedure is verified through comparison with numerical results.
    Keywords: Micro, actuator, Functionally graded material, Dynamic Pull, in instability, Homotopy Perturbation Method with an auxiliary term
  • Mohammad Reza Behjameh *, Hadi Delavari, Ahmadreza Vali Pages 26-34
    In this paper, under the existence of system uncertainties, external disturbances, and input nonlinearity, global finite time synchronization between two identical attractors which belong to a class of second-order chaotic nonlinear gyros are achieved by considering a method of continuous smooth second-order sliding mode control (HOAMSC). It is proved that the proposed controller is robust to mismatch parametric uncertainties. Also it is shown that the method have excellent performance and more accuracy in comparison with conventional sliding mode control. Based on Lyapunov stability theory, the proposed controller and some generic sufficient conditions for global finite time synchronization are designed such that the errors dynamic of two chaotic behaviour satisfy stability in the Lyapunov sense. The numerical results demonstrate the efficiency of the proposed scheme to synchronize the chaotic gyro systems using a single control input.
    Keywords: smooth second, order sliding mode (SSOSMC) control, chaos synchronization, chaotic gyros stability, uncertainty, finite time converges
  • Behrooz Attaran *, Afshin Ghanbarzadeh Pages 35-43
    Rotating machinery is the most common machinery in industry. The root of the faults in rotating machinery is often faulty rolling element bearings. This paper presents a technique using optimized artificial neural network by the Bees Algorithm for automated diagnosis of localized faults in rolling element bearings. The inputs of this technique are a number of features (maximum likelihood estimation values), which are derived from the vibration signals of test data. The results show that the performance of the proposed optimized system is better than most previous studies, even though it uses only two features. Effectiveness of the above method is illustrated using obtained bearing vibration data.
    Keywords: Fault Diagnosis, MLE distributions, RBF neural network, Bees Algorithm
  • Mohammad Mehdi Mashinchi Joubari *, Davood Domiri Ganji, Hamid Javanian Jouybari Pages 44-51
    In this paper, we implemented the Modified Iteration Perturbation Method (MIPM) for approximating the periodic behavior of a tapered beam. This problem is formulated as a nonlinear ordinary differential equation with linear and nonlinear terms. The solution is quickly convergent and does not need complicated calculations. Comparing the results of the MIPM with the exact solution shows that this method is effective and convenient. Also, it is predicated that MIPM can be potentially used in the analysis of strongly nonlinear oscillation problems accurately.
    Keywords: Periodic behavior, Tapered beam, Modified Iteration Perturbation Method (MIPM), Nonlinear ordinary differential equation, Nonlinear oscillation