Page 44 - Shock and Vibration Overview

Response Spectrums

RESPONSE SPECTRUMS

Vibration Response Spectrum

The vibration response spectrum (VRS) is used to quantify how a system will respond for
a given vibration input. It takes the vibration input, in the form of a PSD, and plots what
the response will be as a function of a system’s natural frequency. The vibration
response spectrum calculates the transmissibility functions for a range of frequencies.
Engineers use this in the design process to understand what natural frequencies to
avoid or target for their system.

Let’s use the airplane seat vibration data as an example. If we were an engineer
designing a component for that seat, like the personal video screen, we would need to
understand what natural frequencies to avoid. Taking a look at the raw data and the

PSD (Figure 26) it’s obvious that 250 Hz should be avoided; but how bad would a system
with that natural frequency respond in that environment?

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