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Thesis (M.S.)—University of Nebraska—Lincoln, 1950. Department of Engineering Mechanics.


Copyright 1950, the author. Used by permission.


This investigation was initiated to study the behavior of materials subjected to vibratory motion. In particular, the study was to be an investigation of the properties of felt influencing the performance of felt as a vibration isolator.The performance of felt as an isolation materials cannot be predicted with much satisfaction by the classical theory of vibratory motion and vibration isolation.It was assumed that this might be due to the internal damping of felt and that this damping was not of viscous nature.Therefore, this study was started to determine the nature of the internal friction of felt and the importance of this friction in vibratory motion and vibration isolation.

Since the performance of felt as a vibration isolator could not be determined by calculation in the design stage by common procedures sued with other vibration isolation materials, another goal of the study was to set up a simple test procedure and calculation method that would more nearly give results that agree with actual performance.

S.A.E. F-6 felt was tested as a vibration isolator.This material was subjected to forced vibrations of 0.025 inch amplitudes with frequencies of 10, 20, 30, 40, 50, and 60 cycles per second.Data observed, comprising amplitudes and accelerations of the vibration table and a hanging weight suspended on the felt material, were used to calculate the transmissibility of this material.

Each specimen of felt was subjected to forced vibrations once daily over a period of eight days because a pronounced creep effect was observed.The sustained testing was an attempt to determine how long a period of time was required or steady state conditions to be reached.These sustained tests also determined what effects the creep had on the physical characteristics of this material.

Advisor: W.L. De Baufre