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impact damping devices on the vibration attenuation of flexibly supported machine sets. On contrary to [ 13 – 15 ], in this paper a rotating system with linear cylindrical helical springs is investigated. Moreover, the damping in the connection between the impact element and the damper housing is newly taken into account. A new contribution of the presented work consists of investigating the system oscillations as a result of a combined time variable loading caused by two sources, the rotor unbalance and the baseplate vibrations, and in investigating the interaction

Abstract

The rail dampers are mechanical devices which work as dynamic absorbers to reduce the rail vibration and rolling noise. The paper shows the experimental results from the functionality and performance testing of an experimental demonstrative rail damper. The vibration attenuation takes the highest values, namely 6-22 dB, between 160 and 1000 Hz.

Abstract

This paper investigates the optimal placement of piezoelectric actuators for the active vibration attenuation of beams. The governing equation of the beam is achieved by coupled first order shear deformation theory with two node element. The velocity feedback controller is designed and used to calculate the feedback gain and then apply to the beam. In order to search for the optimal placement of the piezoelectric actuators, a new optimization criterion is considered based on the use of genetic algorithm to reduce the displacement output of the beam. The proposed optimization technique has been tested for two boundary conditions configurations; clamped -free and clamped-clamped beam. Numerical examples have been provided to analyze the effectiveness of the proposed technic.

Resonance Engineering , 23B (1):16-25. 4. I. Kasa (1976), A circle fitting procedure and its error analysis, IEEE Trans. Instrum. Meas. , Vol. 25, 8-14. 5. Kaleta J., Królewicz M., Lewandowski D. (2011), Magnetomechanical properties of anisotropic and isotropic magnetorheological composites with thermoplastic elastomer matrices, Smart Materials & Structures , 20, 1-12. 6. Liao G. J., Gong X. L., Kang C. J., Xuan S. H. (2011), The design of an active-adaptive tuned vibration absorber based on magnetorheological elastomer and its vibration attenuation performance, Smart

composite plates with elastically restrained edges using FEM . – Central European Journal of Engineering, vol.3, No.2, pp.306-315. [15] Sharma A.K. and Mittal N.D. (2014): Free vibration analysis of moderately thick Anti-symmetric angleply laminated rectangular plates with elastic edge constraints . – Mechanics of Advanced Materials and Structures, vol.21, pp.341-348. [16] Asiri Saeed, Hedia Hassan and Eissa Wael (2013): Vibration attenuation using functionally graded material . – World Academy of Science, Engineering and Technology, vol.7.

–adaptive tuned vibration absorber based on magnetorheological elastomer and its vibration attenuation performance, Smart Material Structure , 20, ID 075015, 1-11. 12. Ma T. W., Zhang H., Xu N. S. 2012), A novel parametrically excited non-linear energy harvester, Mechanical Systems and Signal Processing , 28, 323–332. 13. Oueini S. S., Nayfeh A. H., Golnaraghi M. F. A. (1997), A theoretical and experimental implementation of a control method based on saturation, Nonlinear Dynamics , 13, 189-202. 14. Regis V. (2010), Tuning Methodology of Nonlinear Vibration Absorbers

any excitation as a disturbance, continuously trying to reject it. In the subsequent paragraphs, the disturbance d in Fig. 1 will be considered as an impulse disturbance. Fig. 1 Active vibration attenuation in a smart beam. 3.1 Description of the practical stand and model identification The experimental setup has been entirely developed at the Technical University of Cluj-Napoca, Romania. The most important part of the stand is the smart beam which is 240 mm long, 40 mm broad, and 3 mm narrow. The beam is fixed on one end, while the other is allowed to vibrate