We offer a line of specific calculation and analysis services related to the propulsion shafting static and dynamic behavior throughout the vessel lifecycle, from the shipbuilding phase to everyday operation. We also provide services for preparing a tank-heating design calculation.
All the calculations and analyses are prepared in a class review-ready form, as PDF documents, delivered by email.
Torsional vibration behavior is by far the most important aspect of any power transmission shaft line. Therefore, it is no exaggeration to say that torsional vibration is the ultimate parameter determining whether the shaft line succeedes or fails.
For new propulsion plants, carrying out a preliminary torsional vibration analysis is highly recommended to provide important insights into the vibration behavior of the future system and help select the most appropriate system components at an early stage of the design process.
The content of a typical class review-ready torsional vibration analysis is provided in the table below.
| Torsional vibration analysis report |
| Machinery particulars |
| Torsional scheme |
| Conclusions; Notes |
| Calculation data |
| Calculation results, summary |
| Natural vibrations (natural frequencies, mode shapes) |
| Forced vibration diagrams (angular displacements, torques, and stresses), engine normal operation |
| Forced vibration diagrams (angular displacements, torques, and stresses), one cylinder misfiring |
| Transient torsional vibration diagrams (when applicable; e.g., propeller ice-milling or electric motor short-circuit) |
Vibration spectrum
Interest in propulsion plant transient torsional vibration is rising, with growing interest for the sails in iced regions.
Transient torsional vibration analyses provide invaluable insights into plant behavior during short-lived but harsh occurrences that may damage its integrity. To fulfill regulatory requirements, a number of predefined propeller-ice interactions should be simulated and evaluated.
Transient torsional vibration analyses are also important in an electric motor or electric generator plants, where short-circuit events should be taken into consideration.
Transient response of an engine start-up
Axial vibrations are a frequent characteristic of long stroke, slow speed, diesel engine propulsion plants. Moreover, axial vibrations may excite the shafting torsional vibrations when a coupled vibration analysis is an appropriate approach.
The axial vibrations of medium- and high-speed plants are usually negligible.
The content of a typical class review-ready axial vibration analysis is provided in the table below.
| Axial vibration analysis report |
| Machinery particulars |
| Axial scheme |
| Conclusions; Notes |
| Calculation data |
| Calculation results, summary |
| Natural vibrations (natural frequencies, mode shapes) |
| Forced vibration diagrams (displacements, forces, and stresses), engine normal operation |
| Forced vibration diagrams (displacements, forces, and stresses), one cylinder misfiring |
Although excessive lateral vibrations are usually generated by a large shaft line bearing spans, too-small bearing spans may be an issue, too.
The content of a typical class review-ready lateral vibration analysis is provided in the table below.
| Lateral vibration analysis report |
| Machinery particulars |
| Lateral scheme |
| Conclusions; Notes |
| Calculation data |
| Journal bearing characteristics (horizontal and vertical planes) |
| Calculation results, summary |
| Natural vibrations (natural frequencies and mode shapes; horizontal and vertical planes) |
| Forced vibration diagrams (displacements and stresses; horizontal and vertical planes) |
| Natural frequencies for various running conditions |
Calculating the shaft alignment provides shaft lines bearing positions that ensure smooth operation of the shaft line system.
The shaft alignment calculation is also a prerequisite for a meaningful lateral vibration analysis.
The content of a typical class review-ready shaft alignment calculation is provided in the table below.
| Shaft alignment calculation report |
| Machinery particulars |
| Notes |
| Calculation data |
| Calculation results, initial state |
| Calculation results, aligned state (bearing offsets and reaction forces, deflection curve, shear force, bending moment and bending stress diagrams, alignment criteria check, bearing reactions at MCR condition) |
| Assembly parameters and a sketch |
| Jack-up parameters and a sketch (when applicable) |
| Aftmost bearing slope-boring parameters and a sketch (when applicable) |
| Shaft alignment procedure |
Machinery vibration is a consequence of the unbalanced forces and moments that exist during machinery operations. It is frequently associated with the resiliently mounted equipment when the appropriate support elements should be selected to minimize vibration amplitudes.
In the analysis, machinery is treated as a rigid body with six degrees of freedom. The typical analysis report comprises natural frequencies and mode shapes for the six vibration modes (i.e., longitudinal, lateral, vertical, rolling, pitch, and yawing) as well as diagrams of the resulting machinery vibration amplitudes in the horizontal and vertical directions.
Vibration response in the frequency domain
The tank-heating design calculation provides all the necessary information for heating a cargo within the contracted terms.
When applicable, the report is accompanied by drawings of the heating coil arrangement.
The content of a typical tank-heating design calculation is provided in the table below.
| Tank-heating design calculation report |
| General data |
| Excerpts from the technical specification |
| Conclusion; Notes |
| Calculation data |
| Calculation results (heat transfer coefficient, effective coil length, boiler capacity, coil lengths, energy required for a heating cycle, power for temperature maintenance) |
| Required heating times for various environmental conditions |
| Temperature vs. heating time diagrams |
| Heating coil arrangement drawings (when applicable) |
Estimated temperatures as functions of the heating duration
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