Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Design of a Vibration Machine with Base Displacement Control for Stockbridge Damper Vibration Tests
Submission Author:
MARLON MARCHI , PR
Co-Authors:
MARLON MARCHI, Nilson Barbieri, Key Fonseca de Lima
Presenter: MARLON MARCHI
doi://10.26678/ABCM.COBEM2023.COB2023-2305
Abstract
The winds that act on electricity transmission lines generate mechanical vibrations that can damage the lines and interrupt transmission. The Stockbridge damper is used to reduce these oscillations and extend the life of the lines. Experimental studies of the vibrational performance of the Stockbridge use a shaker to generate base excitations with constant velocities or accelerations. However, it is not possible to perform tests with constant displacements on the shaker, especially in the resonant regions of the damper, revealing a little explored gap in experimental and numerical studies of the Stockbridge. To fill this gap, this work aimed to develop a vibration machine capable of generating constant base displacements using the scotch yoke mechanism, with affordable cost and precise control of the excitation frequency. To engineer the machine, a structured design methodology was adopted in ten steps: identification of needs; preliminary research; establishment of objectives; performance specifications; synthesis; analysis; selection; detailed design; prototyping, testing; and production. These steps were accompanied by nonlinear iterative progress, guided by considerations and mathematical models. The functional implementation of the machine involved assembly, calibration, parameterization, remote control testing, as well as dynamic tests with and without Stockbridge. Dynamic tests were conducted at six different displacement amplitudes. For each displacement, the excitation frequency varied from 3 to 50 Hz, with intervals of 0.2 Hz. In each test, acceleration amplitudes were obtained from seven accelerometers, one at the base and the others on the damper. During the tests, acceleration amplitudes of the points of interest were obtained and converted to the frequency domain. The data was then processed in Matlab to generate graphical results of the experimental acceleration amplitude behavior of the base, as well as the frequency response functions of the damper. The results indicated the expected quadratic behavior of the maximum acceleration amplitudes of the base, with or without damper. The frequency response functions showed the natural frequencies and the regions where vibration modes are predominant. In addition, as the displacement amplitudes increased, the maximum amplitudes of the curves occurred at lower frequencies, showing the nonlinear behavior of the Stockbridge. Therefore, the developed machine proved to be a valid and viable option for Stockbridge vibration tests, as it combines unique characteristics such as low cost, easy maintenance, automated operation, and accessible solutions from the current Industry 4.0.
Keywords
Vibration machine, scotch yoke mechanism, Stockbridge damper
