Experimental Modal Survey of a Vertical Cylindrical Shell Partly Filled with Water

摘要

The report deals with an experimental modal survey of a vertical cylindrical shell, requested for experimental verification of the SING-S coupled fluid/structure-interaction computer program. The eigenfrequencies, the mode shapes and the critical damping ratios of the test cylinder used (diameter 1000 x 3 x 1600 mm, empty or partly filled with water, water level 1350 mm) were extracted from the set of simultaneously measured relaxation response signals. The response was achieved via a snapback process. The EVA computer program was used to extract the modal characteristics from the acceleration response signals. A total number of 93 eigenmodes were identified. A secondary objective was the experimental verification by means of a comparative modal survey of the extraction subroutines of the EVA computer program. The modified relaxation procedure with preselected excitation frequencies, the single point random excitation procedure, and the impact method were successively applied to furnish the supplementary modal characteristics needed for the comparison. They yielded consistent results confirming the correctness of all four experimental and evaluation procedures used. (ERA citation 11:034060)