Project Bureau Veritas

Bureau Veritas relies on SimulationX as a system simulation tool for torsional vibration calculations

Vibration analysis of ship propellers

The task at hand

Calculating torsional vibrations of ship propellers and their impacts of all installations and components

Since its foundation in 1828 Bureau Veritas is a world leader in conformity assessment and certification services. With ship certification and classification the company is present in more than 130 countries worldwide. As part of this activity, the mission of Bureau Veritas Marine is to approve design plans for future ships, including structure, machines, electricity, safety and fire issues, stability, and more. It also covers factory inspection at various steps during construction, as well as monitoring ships in service. Torsional vibrations are a constant issue on propulsion and auxiliary machineries onboard ships. The system has to be carefully studied in order to prevent any failure that could lead to economical or even human disasters. 

The role of Bureau Veritas is to ensure that all equipment will have vibratory levels within manufacturer and rules limits. It is therefore necessary to follow the manufacturing progress and to take into account precisely new technological components and their characteristics. As part of its activity in ship certification and classification taking 10% of its annual turnover, Bureau Veritas Marine has to perform calculations regarding torsional vibrations of ship propellers in order to verify the coherency of all installations and components within ships. Using documents provided by machine and equipment manufacturers such as engine manufacturers, suppliers, and naval shipyards, Bureau Veritas Marine needed to update its calculation tool in order to take new international regulations into account.

The solution

Calculation torsional vibrations with SimulationX

Propulsion systems and auxiliary systems driven by diesel engines installed onboard ships are subjected to many periodical dynamic loads. These forces are generating vibrations and consequently additional stresses that should be precisely identified in order to assess the related risks over the entire operating speed range and to avoid any failure on equipment. External forces induce some excitation torques, and then torsional vibrations occur on all the rotating parts of the system. The main sources of excitations on marine installations come from the propeller and the engines. To solve this task Bureau Veritas Marine engineers and ITI developed a custom solution for torsional vibration analysis based on the open platform SimulationX. Therewith the whole range of marine propulsion components was integrated into a dedicated SimulationX library. Model creation has become more intuitive and thus fits Bureau Veritas business-oriented data. Time or frequency simulations can be run with SimulationX solving methods, especially the non-linear frequency domain solver.

The benefits

Making sure that vibratory amplitudes due to forced response calculation comply with manufacturer limits and Classification Society rules

The calculations of torsional vibrations on marine propulsion or generator systems are very specific. Excitation coming from diesel engines or from propeller leads to unavoidable resonance on some equipments. It is therefore necessary to make sure that vibratory amplitudes due to forced response calculation comply with manufacturer limits and Classification Society rules.

Using a tailored modular solution, Bureau Veritas Marine is able to adapt the tool to its work requirements and to take new international regulations into account. Bureau Veritas is able to manage ship data thanks to SimulationX database interface; it thus becomes a work platform which can be used for mechanical studies, as well as for new projects such as energy management systems for ships in service.

Simulation in the marine engineering

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