A Dimension Analysis on Vibration Absorber Design and its Applications in Pipeline

نوع: Type: thesis

مقطع: Segment: PHD

عنوان: Title: A Dimension Analysis on Vibration Absorber Design and its Applications in Pipeline

ارائه دهنده: Provider: mehrdad shemshadi

اساتید راهنما: Supervisors: Dr.mahdi karimi

اساتید مشاور: Advisory Professors: Dr.Farzad Veysi

اساتید ممتحن یا داور: Examining professors or referees: Dr.mohsen bagheri-Dr.Ahmad bagheri

زمان و تاریخ ارائه: Time and date of presentation: 1400/7/24

مکان ارائه: Place of presentation: online

چکیده: Abstract: Abstract: Addition of mass, spring, and damper as a dynamic vibration absorber to a structure that is vibrating out of the permissible vibration range can be an economic and applicable solution to reduce structure vibrations provided that the absorber is designed and adjusted properly. In practice, real structures are damped, which can make it impossible to design vibration absorbers without using numerical solutions and complicated calculations. Using dimensional analysis technique and data obtained from system simulation by MATLAB Simulink, this study aims to provide simple and reliable correlations for designing and analyzing vibration absorbers. For this purpose, the motion equations of a one-degree-of-freedom system with a vibration absorber and a harmonic force applied is simulated. Use of a set of simulation output data to minimize the maximum motion amplitude of the structure along with multiple linear regression method enables determination of unknown coefficients of the correlations derived from dimensional analysis. Studies show that mass ratio and stiffness ratio are important for designing vibration absorbers for undamped and damped structures, respectively. The correlations are validated using the methods introduced in previous studies. Also, an example of vibration absorbers is calculated for an air compressor. The vibration absorber designed by this methodology results in a reduction in the magnification factor of the compressor in resonance by 83%. Vibrations due to mechanical excitation and internal and external fluid flow can cause fatigue in pipelines and leaks in fittings. A beam-based dynamic vibration absorber (beam DVA) is a device comprising an L-shaped beam with a concentrated mass at its free end that can be used to absorb and dissipate vibrations in the pipeline. In this thesis, a mathematical equation is extracted to design the beam DVA using the dimensional analysis (DA) method and data recorded from 219 experimental tests. In the experimental studies, the pipes are fabricated in 1-inch, 2-inch, and 3-inch sizes. Each pipe is subjected to harmonic excitation at different frequencies, and the amplitude of vibration of the pipe is evaluated by changes in the geometric characteristics of beam DVA and concentrated mass. proposed methodology is validated using the finite element method and simulation in the SIMULINK/MATLAB. results showed that, out of the nine effective dimensionless parameters identified in pipe vibration control, mass ratio and stiffness ratio have the highest and lowest impacts on pipe vibration absorption, respectively