Parker EME
Setting up Compax3
192-120113 N08 C3I12T11 - December 2010
263
Non-linearities and their effects
In this chapter you can read about:
Attenuation of the excitation amplitude .......................................................................... 263
Shifting the working point into a linear range .................................................................. 264
Non-linearities in mechanical systems are for example due to friction, backlash or
position-dependent transmissions (cams and crankshaft drives). In general, the
frequency response is only defined for linear systems (see
7.2
(see on page 280)).
What happens in the frequency range in the event of a non-linear system, is shown
below.
Signal amplitude too high => non-linearity in the signal range
Due to the non-linear transmission behavior of the system, many "new" frequencies
were generated in the output signal. In the frequency response, only one change of
the frequency present in the input signal can be displayed meaningfully.
=> The frequencies generated in the spectrum of the output signal lead to a
deterioration of the measured frequency response.
There are however two possibilities to make successful measurements of
frequency responses in spite of non-linearities present:
Attenuation of the excitation amplitude
Signal amplitude too small => no non-linearity in the signal range
