13413 Impact Acoustic Resonance

In several applications of ceramic composites, the damping behavior and the resonant frequency is important. This is especially true for rotating components in turbomachinery. There are primarily two methods that can be used to determine resonant frequency of a component or subcomponent [53, 54]. These are continuous excitation with a swept frequency while monitoring the vibration of the component or by using a sharp impact excitation together with a method to detect the excited vibrations. There are advantages and disadvantages to both methods. Figure 13.28 shows a schematic diagram of one type of acoustic resonance

FIGURE 13.28 Schematic diagram of an impact acoustic resonance setup used to obtain resonant frequencies of ceramic composite components.

device. This particular diagram shows a noncontact laser vibrometer as the non-contact vibration detector. For impact excitation, the function generator delivers a single sharp spike pulse to the "stringer" on the shaker table, which impacts the specimen. For continuous excitation, the function generator sweeps through a broad range of frequencies and the laser vibrometer detects the displacement. Careful analysis of the resulting data allows determination of the fundamental frequencies as well as the damping behavior of the component.

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