An overview of damage evaluation of offshore structures using vibration measurements (frequency shifts), the progress towards a probabilistic vibrational method for the integrity monitoring of offshore systems and measured frequency shifts due controlled inflicted damage on a small scale laboratory model are reported. The scaled laboratory structure model, submerged in a water tank, is excited with an electro-mechanical shaker. The dynamic responses are sensed with 24 accelerometers placed at every connection point. The experiments are controlled with a computer control system with a data acquisition system. The computer processes the response to give resonant frequencies, damping ratios and mode shapes via modal analysis. The system is being automated to perform on-line monitoring and to acquire statistical parameters of the frequency measurements. Frequency and mode shape measurements were performed before and after the damage was inflicted. After a single damage, the structure was repaired and the damage inflicted at another location. This paper presents the results of resonant frequency shifts due to the inflicted damage at three different locations. The damage was inflicted by cutting off one of the diagonal braces of the three-level model.
Damage evaluation of offshore structures using resonant frequency shifts
Ermittlung von Schäden an meerestechnischen Anlagen mit Hilfe der Resonanzfrequenzverschiebungen
1992
7 Seiten, 4 Bilder, 8 Tabellen, 19 Quellen
Aufsatz (Konferenz)
Englisch
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