Analysis of Springing Stresses on S. S. CHARLES M. BEEGHLY and M/V STEWART CORT.
NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD SHIP ACOUSTICS DEPT
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NSRDC was tasked by the U.S. Coast Guard to analyze hull springing stresses of two Great Lakes ore ships for a two year period of operation. The maximum and RMS springing stress, wave bending stress, and unfiltered stress were found for each 30 minute recording interval. In addition to the normal recording intervals, some runs were taken at various headings with respect to the sea and simultaneously with wave buoy data. The natural frequencies and deflection profiles of the BEEGHLY hull were calculated and compared with some available stress data. Quartering or following sea effects are compared with effects of head to beam seas. A procedure was developed to predict the stresses on the basis of calculated wave bending stresses. The distributions of peaks of the wave bending, springing, and unfiltered stresses are given. A procedure was developed to estimate fatigue life accounting for the complexities of the stress signal.
- Marine Engineering