Can a flexible vibration-sensor bracket distort a wind tower measurement?

The short answer

Yes. A flexible bracket has its own motion and can amplify or filter the vibration reaching a sensor. The measured signal may therefore contain bracket response as well as tower response. Sensor calibration alone does not establish that the installed mounting path accurately represents the tower motion at the frequencies of interest.

Define the physical transfer path

Follow motion from the tower surface through clamps, brackets, adapters and the sensor base. Added mass and reduced stiffness can introduce a mounted resonance or reduce useful response bandwidth. A rigid sensor attached to a flexible arm does not make the whole mounting system rigid.

Measurement direction also matters. Bracket bending or rotation can mix motion directions and complicate comparison with a predicted tower mode.

Compare the mounting response with the question

For low-frequency tower sway, a well-characterized mounting may be adequate even if it is unsuitable for higher-frequency detail measurements. The engineer needs the measurement bandwidth and expected signal, not a universal preference based solely on mounting appearance.

A peak that changes when an authorized mounting arrangement changes may indicate transfer-path influence, but that observation alone does not prove the tower is sound. Preserve both the original and revised measurement conditions when comparing evidence.

Specify a suitable measurement interface

Request the mounting method, bracket geometry, sensor mass, direction and known frequency-response limitations. Where needed, a qualified measurement specialist can assess or validate the transfer path before the results are used in a structural decision.

Do not drill or weld a sensor mount into a tower without approval. PCB’s mounting guidance supports the effect of stiffness and added mass; it does not authorize tower modification. This question addresses measurement support mechanics, separate from diagnosing a rain-related vibration symptom or assigning a machine fault from a spectrum.