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Centrifugal Pumps Design and Application 2nd ed - Val S. Lobanoff, Robert R. Ross (Butterworth-Heinemann, 1992)

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Vibration <strong>and</strong> Noise in <strong>Pumps</strong> 473<br />

Figure 18-29. Pump vibrational mode shapes during operation.<br />

analysis techniques, the input spectrum can be evaluat<strong>ed</strong> <strong>and</strong> the impact<br />

can be adjust<strong>ed</strong> to obtain the best results for the structure being test<strong>ed</strong>.<br />

In nonsymmetrical members or structures, a resonant mode has a preferr<strong>ed</strong><br />

direction of motion. Impact testing should be approach<strong>ed</strong> on an<br />

experimental basis by trying variations of impact velocity, direction, etc.<br />

Numerous frequencies may occur that make the mode shapes difficult to<br />

identify. Generally, the lower modes of vibration will be pr<strong>ed</strong>ominate.<br />

The mode of vibration is strongly influenc<strong>ed</strong> by the following:

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