Modal analysis

What is a modal analysis?

A modal analysis is an experimental investigation of the dynamics of structures with respect to their vibration behavior. With this type of analysis, it is possible, for example, to determine characteristic properties of vehicle bodies, bridges or aircraft structures. For a modal analysis, at least one exciter (for example, an impulse force hammer or a shaker) and one accelerometer as well as data acquisition are needed.

Le analisi modali delle strutture meccaniche del Beluga XL sono state eseguite nell'ambito di un ampio GVT dal DLR di Gottinga.
The modal analyses of the mechanical structures of the Beluga XL were performed in June 2018 as part of an extensive GVT (ground vibration test) by the German Aerospace Center (DLR) in Göttingen. 
© Photo by LANCELOT Frederic - MasterFilms, AIRBUS 2018

What parameters are confirmed during a modal analysis?

The following dynamic properties of a structure are typically determined using modal analysis:

  • natural frequency
  • mode shape
  • modal mass
  • modal damping

These values are calculated from the obtained acceleration signals using Fourier transformation. A graphical representation of the frequency response is especially helpful for NVH engineers (Noise, Vibration and Harshness).