Experimental modal analysis

With an experimental modal analysis, components can be described in terms of their structural-dynamic properties, such as natural frequencies, damping and modes shapes. These are also called modal parameters. Knowledge of the modal parameters helps to visualize the mode shapes of a component during the design phase and thus to discover initial weak points. They are the basis for vibration-optimized designs or subsequent vibration-reducing measures.

Experimental modal analysis – excitation of natural vibrations with the impulse hammer

In experimental modal analysis, these natural vibrations are excited, for example, by an impact with the impulse hammer and the vibration responses of the structure are recorded by sensors, usually accelerometers.

The structure to be analyzed is softly supported or suspended on threads so that the natural mode shapes can develop.

The relationship between the vibration response and the force excitation is recorded by the transfer function as a function of the frequency in each degree of freedom of the structure.

For weakly damped systems with isolated natural frequencies, the natural frequencies result from the maxima of the amplitude frequency responses, and the modal damping parameters result from the width of the peaks.

Operational modal analysis

Furthermore, it is possible to determine the operational mode shapes. The analysis of the operational mode shapes (operational modal analysis) differs from the experimental modal analysis. The structure is fixed to its attachment points for this purpose. Shakers, among other, can be used to excite the structure. The operating mode shapes can be displayed based on the recorded vibration responses of the structure.