Yazar "Dutkiewicz, M." seçeneğine göre listele

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    DETERMINATION OF OPTIMAL ELASTIC SPRINGS FOR CANTILEVER BEAMS SUPPORTED BY ELASTIC FOUNDATION
    (Acad Sci Czech Republic, Inst Theoretical & Applied Mechanics, 2018) Aydin, E.; Ozturk, B.; Dutkiewicz, M.
    In this study, the optimum distribution of the elastic springs in which a built-in cantilever beam is seated, so as to minimize the shear force on the support of the beam, is investigated. The Fourier transform is applied to the vibration equation of the beam written in the time domain and is shown by the structural behaviour transfer function which is made independent from the external influence. For the first and second modes of beam, the optimum locations and amounts of the springs were investigated so that the shear force transfer function amplitude was minimal. Stiffness coefficients of springs are taken as design variables. There are active constraints on the sum of the spring coefficients taken as design variables and passive constraints on each of them as the upper and lower bounds. Optimality criteria are derived using the Lagrange Multipliers method. The gradient information required for solving the optimization problem is analytically derived. Numerical results show that the aimed method is quite effective in finding optimum spring stiffness coefficients.
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    OPTIMAL PASSIVE CONTROL OF SHEAR BUILDINGS
    (Acad Sci Czech Republic, Inst Thermomechanics, 2017) Aydin, E.; Ozturk, B.; Dutkiewicz, M.
    In the paper, the analysis of damping parameters for vibration reduction of buildings with use of optimization algorithm is presented. Optimal values of damping coefficients are determined at fundamental structural mode of shear buildings in order to attain desired added damping ratios. The cost function is defined as the sum of damping coefficients of the dampers to be minimized. Proposed optimization problem is solved by using three different numerical algorithms that are namely: Simulated Annealing, Nelder Mead and Differential Evolution algorithms, respectively. Numerical example is presented to prove the validity of the proposed method. The changes of optimal distributions of the dampers with respect to target damping ratios and structural periods in a particular range are investigated for two-story shear building model. The numerical results show that the proposed damper optimization method is easy to apply and efficient to find optimal damper distribution for a target damping ratio.