This study aims to verify the equivalence between a Gaussian random vibration extracted from a vehicle vibration and that generated by a current vibration controller. The equivalence was evaluated by calculating the kurtosis from a single degree of freedom (SDOF) response, assuming that an SDOF system serves as the packaged product. Depending on the natural frequency of the packaged product, the SDOF response to the Gaussian random vibration generated by the current vibration controller was found to be a Gaussian random vibration, while the SDOF response to the Gaussian random vibration extracted from the vehicle vibration, a non-Gaussian random vibration. The results demonstrate that both the Gaussian random vibrations may not be equivalent. Further, solely the power spectrum density (PSD) and probability density function (PDF) are not sufficient to completely understand the nature of the vibrations; the PDFs of the SDOF responses also need to be considered.

View full abstract

A random vibration test is important for confirming the safety of packaging when transporting goods on a truck bed. There are differences between the traditional random vibration method and real vibration measured on the truck bed. These differences may result in overpackaging or underpackaging. Therefore, improving the input vibration during vibration testing is an important theme. In this study, we focused on the kurtosis response spectrum. A previous study showed that the response kurtosis under the real vibration varies depending on the natural frequency. Therefore, it is assumed that a random vibration with the same kurtosis response spectrum as the real vibration is similar to the real vibration. We propose a new method for generating random vibration considering the kurtosis response spectrum. Vibrations with the same power spectral density, root mean square of acceleration, acceleration kurtosis, and velocity kurtosis (but different kurtosis response spectra) were generated by the proposed method and the previous study method. Comparing the kurtosis response spectra between the real and generated vibrations, the proposed method showed a particular improvement in the input vibration, especially when the damping factor was small. Keywords: Transportation, Vibration test, Response Spectrum, Kurtosis

View full abstract