TORSIONAL VIBRATION OF MARINE
PROPULSION SYSTEMS

1. Introduction

2. Torsional Vibration Fundamentals
   1. General Description of Free and Forced Torsional Vibration
   2. Preparation of Lumped Parameter Models
   3. Undamped Torsional Vibration Analysis
   4. Coupling Modes vs. Shaft Modes
   5. Methods for Checking Computer Results by Hand
   6. Generation of Campbell Diagrams
   7. Torsional Vibration Excitation Sources
   8. Synchronous Motor Startups
   9. Types of Variable Frequency Drives
   10. Torsional Problems Associated With Variable Frequency Drives
   11. Determination of Interference Points
   12. Elimination of Interference Points by Inspection
   13. Representative Excitation Torque Magnitudes
   14. Common Damping Sources
   15. Determination of Damping Coefficients
   16. Steady-State Damped Response Analysis
   17. Transient Torsional Vibration Analysis
   18. Short Circuit Analysis
   19. Determination of System Adequacy
   20. Shaft Endurance Limit Determination
   21. Detailed HCF and LCF Fatigue Life Analysis Procedures
   22. Methods for Eliminating Problems
   23. Elastomer-in-Compression Couplings
   24. Hydraulic Couplings
   25. Overall Analysis Procedure
   26. Case Studies

3. Torsional Vibration of Marine Propulsion Systems
   1. Typical Marine Propulsion Systems
   2. Need to Assess Multiple Operating Modes
   3. Modeling of Diesel Engine Crankshafts, Connecting Rods, and Reciprocating Parts
   4. Added Mass Effects in Propellers
   5. Typical Mode Shapes in Marine Propulsion Systems
   6. Diesel Engine (Gas Pressure & Inertia) Excitations
   7. Diesel Engine Fourier Coefficients
   8. Diesel Engine Major & Minor Orders
   9. Diesel Engine Damping
   10. Propeller Excitations & Damping
   11. Handling of Variable Pitch Propellers
   12. Forced, Damped Response Analysis Plots
   13. Determination of FC and FT Stress Limits for Intermediate & Propeller Shafting
   14. Barred Speed Ranges
   15. Effect of Changing Diesel Engine Loading Conditions
   16. Diesel Engine Misfire Condition
   17. Reciprocating Equipment Criteria for Acceptability
   18. Methods for Eliminating Problems
   19. Viscous Dampers
   20. Overall Analysis Procedure
   21. Coupling Between Torsional & Longitudinal Vibrations
   22. Case Studies

4. Conclusion

1. A greater familiarity with torsional vibration fundamentals, which would allow them to communicate more effectively with experts in the field.

2. A better understanding of the meaning and validity of torsional vibration results obtained from consultants and/or in-house computer codes.

3. An appreciation that, contrary to the approach of most engine manufacturers, torsional analysis is not a trivial task that can be handed to any junior engineer with a computer code.

4. A better understanding of the torsional vibration causes of common problems in marine propulsion systems which would assist them when trying to troubleshoot field problems.

5. A better feel for which components in a marine system play an important role in torsional vibration behavior and which ones have little impact. This would be valuable when evaluating potential design changes.

6. An appreciation that torsional vibration analysis can be performed in a practical and timely manner and does not require a "research project."

7. An appreciation for the large role that torsional vibration behavior plays in the reliability of marine propulsion systems and for the importance of evaluating that behavior in the design stage.

The short course is presented using multi-color Power Point presentation software. Each employee the client sends to the short course receives a complimentary copy of our paper, "Practical Design Against Torsional Vibration," and a pdf file containing all the slides presented in the short course.