An elevator is a typical flexible lifting machine. In order to monitor the vibration of elevator structure, the vibration characteristics of an elevator with a traction ratio of 1:1 has been tested experimentally. Sensors were arranged on the platform frame, car roof, and hoist rope to test the vibrations of the elevator in both ascending and descending conditions. The transverse, longitudinal, and coupled transverse-longitudinal vibrations were compared and analyzed. Further, the short-time Fourier transform (STFT) method was used to examine the power spectral density (PSD) of the test results, and the main frequency distribution and influencing factors of the vibration of elevator components were investigated. The results revealed that the transverse and longitudinal vibrations of the platform frame were low-frequency vibrations, which was attributed to the elastic interaction between the platform frame and the car frame. The form and amplitude of longitudinal vibration of the car frame were basically consistent with those of the platform frame, but PSD of the transverse vibration had an obvious peak in the high-frequency region. The transverse and longitudinal vibration frequencies of the hoist rope were higher. Furthermore, the peak PSD value of transverse vibration of the hoist rope was 421 times larger than that of the car frame, so a small disturbance at the end of the rope could lead to a huge disturbance in the center of the rope. Overall, this study provides useful insights on designing an elevator monitoring sensor and relevant data processing.

This paper deals with the buckling phenomenon of undersea corroded pipelines. The corrosion degree of the pipelines is characterized by two parameters: the angular extension and the corrosion depth. Previous work has shown that symmetric and antisymmetric buckling modes occur in pipelines when the corrosion is uniformly extended over part of pipelines along the circumferential direction. The presented research analyzes the stability condition in pipelines with generalized corrosion. Using WKB theory for asymptotic expansion, the buckling mode and the eigenfunctions are derived for the corroded pipelines subjected to external hydrostatic pressure. Furthermore, asymptotic solutions are derived for pipelines with constant corrosion and compared with validated solutions obtained in previous work using equilibrium analysis. It shows that the buckling modes and buckling pressure from asymptotic analysis are identical to the exact solutions. Symmetric and antisymmetric buckling modes are found to occur for pipelines when the corrosion is not uniform but symmetric about its centerline.