Natural frequency measurement of steel components by the sound signal

A new test method based on sound signals for natural frequencies of steel components was proposed in this paper. The proposed method is a non-contact measurement method which does not need to install any sensors and therefore generates no measurement errors. The method consists of three steps. First, a steel component is placed in suspension state, and the sound signals of this component are collected under artificial excitation by a recording device such as a mobile phone. Second, the collected sound signals are analyzed by the periodogram method to obtain the power spectral density curves. Finally, the first few natural frequencies of the steel component are readily obtained through the power spectral density curves. An I-steel beam was tested in the experiment to verify the proposed method. The first three natural frequencies of this beam can be successfully obtained by the proposed method. For comparison, the values of the first three natural frequencies of this beam were also analyzed by numerical simulations and the traditional modal test method using the acceleration sensors. It has been found that the results obtained by the proposed method only have slight deviations compared with the values obtained by the simulation and the modal test method. Compared with the traditional modal test methods, the proposed method is more economical, fast, and precise to obtain the natural frequencies of steel components. It may be a promising testing method for the natural frequencies of steel components.