Vibration measurements

Vibration measurements are performed in many disciplines, like mechanical engineering or civil engineering, to eliminate disturbing vibrations, prevent damage to structures and ensure the well-being of individuals.

In civil engineering, dynamic measurements are made on bridges, for example, in order to obtain information about the natural frequencies of the structure. If the natural frequency of a pedestrian bridge is within the range of the pedestrian's step frequency, then the vibrations can oscillate and adversely affect the comfort perception of the pedestrian. In extreme cases, vibration absorbers have to be retrofitted to dampen accelerations (Millenium Bridge, UK). This installation is very expensive, so that vibration examinations pay off in the early planning stage.

If highly sensitive devices are set up in laboratories, these must be stored vibration-free. The bearings required for this purpose must be matched to the natural frequencies of the affected ceiling in order to avoid vibrations of the equipment. Again, vibration measurements are needed.

The general rule:

The excitation frequencies should not fall within the range of the first natural frequencies of a component or structure in order to avoid resonance effects and thus large amplitudes.

Comparative Measurements

In the development process of the app numerous comparative measurements were carried out to ensure the correct determination of the results. Here, ceilings, columns, bridges and their hangers were examined for their natural frequencies and the results of the myFrequency app were compared with those of professional measurement sensors. This resulted in maximum deviations of the frequency peaks of about 1.1%.
 
These studies prove that the myFrequency app is an adequate replacement or supplement to costly professional measurement sensors.

Comparative measurements of hanger of the Frey Bridge in Berlin, Germany

At the Frey Bridge in Berlin, the natural frequencies of hangers were determined. They were measured on the one hand with the myFrequecy app and on the other hand with professional accelerometers. Both "gauges" were installed on a hanger.

 After excitement of the hangers, the decay behavior was recorded and the frequency spectra were compared. Below, the two spectra are compared.

myFrequency - Smartphone App

professional accelerometer


The comparitive measurements on the hangers showed maximum deviations of the frequency peaks of only 0.09%. With the help of the app myFrequency, the costs and the time required to determine the natural frequencies of hangers can be reduced enormously (see below).

Comparison / conclusion

The comparative measurements showed that the myFrequency app is an adequate alternative to expensive measuring technology, since time and costs can be saved on a large scale. In the case of the measurement of the natural frequencies of hangers, a reduction of the time effort by about 96% can be achieved, with the same measurement result.