This was a joint Industry Project (JIP); to conduct a laboratory study of vibration response of a scale model of an offshore tower subjected to random excitation. The random decrement technique will be applied to the recorded and filtered vibration response data to establish a set of signatures. From these signatures the sensitivity of the signatures to induced fatigue cracks of various lengths and locations can be studied.
Complete. Experimentation was conducted on a model offshore structure which was tested in air and water and on solid and sand footings. Effects of simulated structural damage were studied on natural frequency and mode shapes. Results demonstrated the ability of the method to detect and measure progressive failure in the model. The Random Decrement technique also was evaluated under the NDE Round Robin Program, Project No. 34 and results are encouraging. It is being applied to several offshore structures made available by the Navy and the Coast Guard to determine possible field related problems.