Experimental modal analysis of in-plane bending mode of cylindrical shell which is coupled elastic bar

To prevent aging in buried water pipes that have exceeded their service life, it is crucial to assess pipe conditions using non-destructive testing and apply the findings to pipe renewal and repair strategies. This study investigates the coupled vibration of a water pipe with an attached bar-like structure. The pipe and bar are modeled as a circular ring element and an elastic bar element, respectively, connected via spring elements. The experimental modal analysis (EMA) was performed to reveal the coupled vibration phenomena between the in-plane bending mode in water main and the longitudinal mode in elastic bar. As the results, the existence of the coupled mode between the in-plane bending mode and the bar deformation mode around the 1 kHz. In addition, the isolated longitudinal mode of bar structure was obtained the high frequency band over 3 kHz.