Excitation measurements
Experimental analysis of resonance frequencies and stiffness
Every structure has one or more resonance or eigen frequencies. An excitation measurement or impact test is one of the most important analysis technologies in a foundation or resonance research. An excitation test is an experimental method to determine the dynamic stiffness and resonance frequencies of a structure. An excitation measurement produces very valuable information about the vibration "sensitivity" of a structure, information that also can be used as input for an ODS- or modal analysis.
Excitation measurements are in contrary to most other measurement technologies performed on non running machinery or structures. The structure is excited with a special hammer, fitted with a force sensor that measures the dynamic force of the excitation. Simultaneously with the force excitation the vibration response of the structure is measured. With the combined measurement data it is now possible to calculate the Transfer or Frequency Response Function. The analysis of the resulting spectrum functions will reveal all eigen-frequencies, amplification factors en phase shifts, which together enable a reliable view on a.o. the dynamic stiffness.
Excitation measurements are most suitable for the dynamic stiffness analysis of machinery structures. This applies for machinery still in the design phase, during commissioning or for trouble shooting field problems.
These measurements have also proven their usefulness for the analysis of machinery where running measurements are not (yet) possible. Transient measurements, tracking analyses and ODS-measurements always require a running machine.