THE INFLUENCE OF COUPLING STIFFNESS ON NATURAL FREQUENCIES IN A MISALIGNMENT CASE OF TWO-DEGREE-OF-FREEDOM SYSTEMS
Misalingment is a failure which often occurs in rotating machine. As one of common failure, misalignment modeling will help understanding the behaviour that occurs to the system when such case happened. Therefore, the background of this research is about the effect of coupling stiffness value in dyn...
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| Format: | Theses |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/63969 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Misalingment is a failure which often occurs in rotating machine. As one of common failure, misalignment modeling will help understanding the behaviour that occurs to the system when such case happened. Therefore, the background of this research is about the effect of coupling stiffness value in dynamic of two degree of freedom model. Modeling will be done for paralel misalignment with some coupling stiffness value.
This research begins with modeling the equipment as a two degree of freedom system. The research is then continued by deriving equation that relates coupling stiffness with the natural frequency of the system for selected model. The equation will be used to describe several conditions, which is first condition where stiffness value is zero or where two system is not connected, second, condition where stiffness has positive value and last where stiffness value move toward infinity. Numerical simulation is then conducted using MATLAB for determined parameters. Simulation will be conducted for model in two stages. For the first stage, the excitation force will have the frequency as running frequency. For second stage, for misalignment case, the excitation force will contain 2 frequencies, which is 1x and 2x running frequency.
The natural frequency equation derived shows that as stiffness value move toward infinity, the first natural frequency will move to a certain value while the second natural frequency will move toward infinity. The equation derived also reveal the mode shape of the system. The first mode shape shows that both masses will move together if coupling stiffness value is high while the second mode shape shows that both masses will move in opposite direction. At some running frequency, 1x running frequency response will look dominant, while at the other running frequency, 2x running frequency response will be dominant.
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