چكيده به لاتين
Abstract:
Considering the wide range of turbochmachineries applications, solutions to reduce the resonance peaks and ... at the high speed of these machines, become a significant and interesting subject of research.
In this Thesis vibration dissertation, a multi-layered composite rotating blade at an arbitrary stagger angle is investigated to find natural frequencies and vibrational modes. The blade is modeled with a classic plate theory having an initial angle. For this purpose, the geometry of the problem is first introduced and then the equilibrium equations of the plate are extracted by the principle of Hamilton according to the classical hypotheses. Then the equations are solved by the Gelerkin method in order to solve the problem of the desired specific value. The results obtained by this method are compared with the results in the references and validation. In this study, the effect of different parameters involved in the problem, such as turbine rotational speed, initial angle of the blade, and the geometry of the blade on the frequency and mode shape in the composite and multi-layer blades, were analyzed. Finally, by placing the constrained layer damping in the direction reducing the amplitude at the resonance points will re-examine the system. The results of parametric analysis indicate that the main parameters for the effect of damping ratio, material thickness, and the speed of rotation. the modal damping ratio with decreasing rotating speed does not show regular changes and increases with the increasing of the thickness of the constrained layer. At the end, the effects of adjacent mistuned blades and holder between them modeled by using mass and spring.The proposed model provides an efficient method for studying the dynamic behavior of rotary multi-layer composite structures, such as compressor blades, helicopter blades, and more.
Keywords: Compressor Blade Vibrations, Composite Plate, Classic Theory
