ShaftDesigner – Torsional Vibration Software

Mass-elastic system scheme

Unified editor to set values/dependences

Calculation types

Free vibration calculation

Forced vibration calculation

Results

Ice Impact calculation

Short Circuit calculation

Reports

 

The torsional vibration analysis is required by Classification Societies.

The ShaftDesigner Torsional Vibration Application is a powerful aid to estimate effect of torsional vibrations to the propulsion system.

The module can get rid users of the time-consuming computation since a huge advantage of the Application is a high-speed calculations performed without third-party FEM solver behind. The high speed is achieved by introducing new algorithms into the system to optimize operation capabilities.

In the process of project developing the customer is offered a wide range of functions integrated in the module providing multi-optional approach at all project stages starting from mass-elastic system scheme (MES) creating and ending with obtaining a report.

MES

The ShaftDesigner Vibration Application suggests several ways to create MES depending on quality and quantity of available information.

From Base Model

In one button click MES can be compiled from Torsional Vibration Model for existing Base Model.

For the project with Base Model it is possible to see simultaneously the Base Model window and the Torsional Vibration Application window. These windows arranged horizontally is the option tailored for displaying projects on the ultra-wide monitor

With special MES editor

Special graphics editor additionally provided by Torsional Vibration Application enables user to create a mass-elastic system when the Base Model is not available. With MES editor a user will have at hand a complex of friendly solutions to implement project ideas when system components number, types and properties can be changed in the quick manner. Among MES quick modeling methods are such as:

  • creating a number of nodes/elements simultaneously in the same chain dialog window;
  • blocks connecting according to the kinematic scheme;
  • group editing for nodes/elements;
  • scheme adjusting with special buttons/mouse dragging, etc.

To be in line with the customer’s preferences, MES appearance can be customized; units scheme and digit display format can be adjusted to ensure suitable MES view.

In the context menu opened from the several convenient MES locations a user will get access to the dialog windows allowing nodes / elements / blocks properties settings.

In-stock methods

To facilitate MES creating, earlier developed and saved parts or entire MES can be inserted from Repository.

The module is also provided with Excel files from which components can be imported to MES.

The copy/paste functions work for parts or entire MES in the same or different project. Entire MES can be copied together with already set acceptance criteria and Harmonic Response Analysis settings.

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No simplification

One of the recent ShaftDesigner’s releases contains updating which is very important for engineers facing some difficult cases when a shafting or equipment in the Base Model is of complex design (e.g. the turbine generator shaft).

The feature of avoiding automatically made simplification for MES generating allows user to get higher accuracy of calculation. It is used when full information on the 3D model is available based on the manufacturer’s documentation.

The feature appeared in the process of discussions after the customer applied for consultations and obtained expanded support of IMT specialists to the full customer satisfaction. One of the IMT’s strengths is the feedback flow obtained from the customers permanently and allowing developers to make improvements based on the real nowaday projects.

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Diesel engine

To enable the customer to use the manufacturer’s information for MES creating, the Engine Calculation Scheme editor is specially intended to change or create diesel engine mass-elastic scheme. This editor is used only for existing Torsional Vibration Model.

With checking the checkbox, ‘Master engine’ (for more than one engine present in the system) and ‘Generating mode’ can be appointed for diesel engine in MES.

Combinations

To save time when MES developing all described methods can be used in combination. For example, one part of MES is developed in graphics editor and then another part is inserted from Repository, after that the parts are connected and scheme is adjusted by quick modeling tools to the desirable view.

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The software allows the automatically generated parts of such a mass-elastic system to be combined with the systems supplied by engine, gearbox and other rotating machinery manufacturers.

Unified editor to set values/dependences

Any engineer knows that before click the ‘start calculation’ button, thousands figures are to be entered to form tables and diagrams on which the calculation is based. This problem is solved in the ShaftDesigner Torsional Vibration module with implementation of unified tabular value editor with standard buttons set. It is possible to add/delete lines, copy/paste a table, to save/load the table to or from file, to use extrapolation methods. But the most valuable function is the default one: it allows user without delays for searching or requesting information to get relevant diagram in a second and continue the process. It is especially important when the timing is pressing to see the project prospects as soon as possible.

In the module the editor can be used for settings, for example, of:

  • damping and stiffness for setting nodes/elements properties in MES;
  • direct input of propeller excitation;
  • Speed – Pressure law;
  • Torque-Speed diagram;
  • Thrust-Speed diagram;
  • Power limit curve;
  • Gas pressure diagram;
  • direct setting of the value for electromotor excitation.

Calculation types

The ShaftDesigner Torsional Vibration module provides torsional vibration analyses (TVA) comprising three types of calculations:

  • free vibration calculation,
  • steady vibration calculation caused by a harmonic excitation,
  • advanced ice impact and short circuit features providing transient calculations in the time domain.

Torsional vibration calculations may be performed for a complete propulsion train or its parts, with different states of clutch connections.

Free vibration calculation

The simplest way to check the propulsion system with fixed mass and stiffness parameters for resonance appearance is to perform calculation of a free non damped torsional vibration.

Forced vibrations calculation

Calculation of forced vibration excited by a diesel engine, electromotor, propeller or impeller, depending on what is applicable, is performed.

Power Table

The customer using ShaftDesigner Torsional Vibration module does not need to speculate and worry for if the sources power will not be enough for the consumers. The Power Table gives confirmed by figures and graphs answer to this question and makes possible to see different load variants as well as overloaded zones.

The Power Table is specified in the case when several power consumers are present. It demonstrates the distribution of power generated in the system between consumers for the case when the primary mover is present in MES.

power table.png

Cylinders names absence as a warning

In the tables in the dialogs for firing order and angles and cylinder excitation, absence of the cylinders names in the tables indicates:

  • no correspondence between the number of the crank type nodes in MES, the number of cylinders and engine design (V-type or in line);
  • values in the appropriate fields are changed.

Pressure deviation setting

For cylinders the both increasing (‘plus’ sign value) and decreasing (‘minus’ sign value) can be set for the pressure deviation in percent and/or constant value.

Speed-Pressure law

There are several options to set the Speed-Pressure law by default. The table for diagram creating can be filled:

  • with values obtained as a result of engine power recalculation according to the Power Table data;
  • according to the formula for the nominal propeller law;
  • according to the engine’s Torque – Speed diagram.

Torque-Speed diagram

The latest ShafDesigner updating is to define the Torque-Speed diagram on the base of the Speed-Pressure diagram.

Excitation

Excitation is set depending on what equipment is present in the project.

The software part responsible for diesel engine settings is based on the deep understanding of user’s needs to see situation in normal/malfunction conditions, in nominal and different from nominal (service) modes. It is possible to define a special operating mode in the appropriate dialog or copy nominal mode values. Malfunction conditions include for cylinders such options as misfiring, exhaust valve opened, dismantled. Calculation can be performed with some cylinders only for which malfunction mode is set or for one by one misfired engine cylinders.

Helpful tools allow user to fill a harmonic coefficients table in a time-saving and convenient way depending on what information is available. Among options are such as;

  • copy/paste function;
  • Windows ‘Ctr +V’/ ‘Ctrl +C’;
  • using indicator diagram;
  • save/load to/from Xml-file;
  • clear the table / clear to zero values.

It is possible to toggle between Real & Imaginary and Resultant & Phase representations.

The excitation orders can be switched on and off to play with gas excitation. Changing the state of any order reflects on the graph. This allows user to understand the input of particular order.

When the normal firing excitation harmonic components are unavailable, the excitation can be determined approximately using typical average values for harmonic coefficients proposed by Lloyd Register, or the user-specified engine manufacturer’s harmonic components can be used. The certain manufacturer can be selected in the menu.

It is possible to recalculate pressure type (BMIP or BMEP) from one to another for already filled harmonic coefficients table and normal Speed-Pressure law set.

If a user has available harmonic coefficients in the form of torque values and the table is already filled, it is also possible to make recalculation when coefficients option changes from Moment to Pressure or vice versa. Then there are options to change units and change excitation or recalculate coefficients and remain excitation.

The forced vibration can be calculated by two different methods: mode superposition method and full solution method. A lot of possibilities to set excitation and damping parameters for these methods are one of the software advantages that make it flexible and easy to use.

Acceptance criteria

Forced calculation enables to compare calculated values with permissible values determined either according to Classification Societies requirements or set by the user. Barred zone or not allowed zone is indicated according to calculation results.

Acceptance criteria limitations’ values can be set automatically according to the specific requirements of chosen Classification Society or can be defined by a user. Class requirements are permanently monitored by IMT for amendments, the software is updated for respective Rules changes.

Results

Free vibration calculation

The main results of the free vibration calculation are the following characteristics: natural frequencies and mode shapes as well as resonance speeds in the form of Campbell diagram and resonance table.

Forced vibrations calculation

Vibration node amplitudes, accelerations, vibratory torques and vibratory stresses in the elements are determined as the result of forced vibration calculation. Gear Vibratory torque and Gear hammering are determined for gearing; Power Loss values are determined for flexible couplings and dampers.

Usually Forced Vibrations calculation is performed for normal operating conditions of every enabled State or for the selected (current) State. In the Torsional Vibration Application states are completely independent, starting with the calculation schemes and ending with calculation options. State can be duplicated and edited as required.

There are several tabs for different information needs for torsional vibration analysis: Rotation, Time Waveforms, Branch Amplitudes and Scale Matrix tabs.

rotation with dangerous zones.png

With the module tools it is possible to adjust screen for results preview: what tabs or what graphs are to be shown/hide.

Forced vibration calculation results are displayed in the ‘Normal Operation’ tab in the results preview screen. When a user sets as necessary to perform calculation under engine malfunction conditions, two calculations will be performed simultaneously and two tabs will be displayed: ‘Normal Operation’ and ‘Malfunctions’.

Results for calculation performed for one by one misfired engine cylinders:

one by one misfiring result.png

Ice Impact calculation

The ShaftDesigner software provides a powerful tool for calculation of propulsion shafting system torque response caused by ice impacts on the propeller blades.

The torque response on any component in the propulsion system is determined by analyzing the transient torsional vibration, taking into account the ice excitation torque on the propeller, the actually available engine torque and torsional vibrations caused by engine excitations. The calculations are carried out for all the excitation cases and the excitation torque applied to the mean torque in the state of the bollard condition at the considered rotation speed of the propeller.

Any simplification of the MES is not required. The calculation fully meets Classification Societies Rules requirements.

In the results preview screen both rotation and time-domain responses are available.

ice result propeller shaft.png

All results are displayed for the most dangerous ice impact torque corresponding to the case number.

Short Circuit calculation

The calculation is performed according to settings of excitation torque for short circuit for VFD Electromotor.

Calculation results are grouped into two tabs:

  • Time Waveforms;
  • Critical Objects.

short circuit result.png

Reports

The main thing before wrap up a project is to prepare a report. A user can do this in the correct and desirable way selecting required content, structure, appearance, form of the report.

Free vibration calculation

Calculation results can be seen in the automatically generated reports. The content and appearance of the report can be adjusted before calculation start. The content of calculated results complies with the Classification Society requirements to the free vibration calculation.

Forced vibrations calculation

Forced vibration calculation report includes the content previously selected by a user in the respective lists in the diagrams/tables.

In the results preview screen and with other tools a user is enabled to:

  • check nodes/elements, rotation speeds to be included in the report;
  • specify the form of presenting information (table/diagram);
  • on the graphs show/hide an orders for which acceptance criteria are satisfied;
  • set a graph scale;
  • group results by parameter or by object;
  • make report for selected state/for all states;
  • control a report content in the special window with possibility to check/uncheck items (remain/exclude from the report) or export selected items in the Excel file;
  • customize report appearance;
  • save/load/restore report profile;
  • export calculation reports to the commonly used data formats: MS Word, PDF, XML, HTML, EMF files, with possibility to set format options of the file;
  • merge the reports;
  • add a conclusion to the report.

For ‘misfire cylinders one by one’ option calculation results are reports for every misfired cylinder and consolidated ‘Misfire cylinders’ report. In this report, changes in main vibration parameters with an indicated number of the misfired cylinder are shown in one diagram.

Violated acceptance criteria are highlighted in red among the results in the report.

On the user’s choice warning can be shown for dangerous speeds and unsatisfied acceptance criteria.

For the Ice Impact and Short Circuit calculations, principles of operations with reports are the same as for the Forced vibration calculations.

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With a full set of the Torsional Vibration Application features, a user obtains a high-intellectual, flexible tool where in the process of manipulating software the best methods, options and the shortest ways for work with the module can be found.

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The software advantages can be tested during using the fully functionally trial version for 40 working hours.

After sales, on-line support is provided for ShaftDesigner software.