'''Modal testing''' is a form of [[vibration|vibration testing ]] of an object wherewhereby the natural (modal) frequencies, modal masses, modal damping ratios and mode shapes of the object under test are determined.
A modal test not only consists of an acquisition phase,but also ofand an analysis phase as well. The complete process is often referred to as a [[Modal Analysis]] or Experimental Modal Analysis.
There are several ways to do modal testing.Impactbut Hammerimpact modalhammer testing and Shakershaker (vibration tester) modal testing are usedcommonplace. In both cases [[energy]] is supplied to the system with a known frequency content. Where structural resonances occur there will be an [[Amplifier|amplification]] of the response, clearly seen in the response spectra. Using the response spectra and force spectra, a [[transfer function]] can be obtained. The transfer function (or [[frequency response function]] (FRF)) is often [[curve fitting|curve fitted]] to estimate the modal parameters; however, there are many methods of modal [[Estimation theory|parameter estimation]] and it is the studytopic of much research.
[[Image:M1w1Layout.jpg|frame|center|alt=Layout of a modal testing system|Sample layout of a modal testing system]]
