Re: Torrent Maxsurf V8i Added
Osoulo Lejeune
A loadgroup is a group of fixed weights that can be then included as a single row in one or more loadcases. A good example of this is the Lightship weight which can be defined in a loadgroup and included in several loadcases (e.g. Departure and Arrival conditions). Should any changes be required to the lightship, this is done in the Lightship loadgroup which will then automatically update the loadcases that include it.
Vessel is balanced at equilibrium, then the net longitudinal loading, shear force and bending moment distribution is computed and compared with user-specified curves of limiting shear force and bending moment
Results calculated are the hydrostatics at the specified condition (including sectional area curve). These types of data can be quite useful when performing an inclining experiment or lightship survey as the displacement and centre of buoyancy are easily calculated from the draught measurements.
A new analysis, following the procedure outlines in IMO Resolution MSC.362(92) Revised Recommendation on a Standard Method for Evaluating Cross-Flooding Arrangements, has been added to this version of MAXSURF Stability. Cross-flooding devices connecting pairs of rooms are defined for the model. The analysis takes an initial damage condition and evaluates the final cross-flooded condition, as well as the time to achieve full cross flooding using the procedure in MSC.362(92). Specify any number of intermediate times, e.g. 60s and 600s, and the vessel condition, including room flooding level, will be computed at these time-steps. The analysis takes into account multiple pairs of cross-flooding rooms, and automatically finds the volume of cross-flooded fluid for each pair of rooms at each time step. View the vessel condition graphically at each immediate time step, as well as pre and post complete cross-flooding. Full vessel properties including flooding volumes and centers are tabulated for all the conditions.
Spilling of liquid cargo from tanks has been added to this version of MAXSURF Stability. Select outflow points to be connected to spilling tanks to determine the maximum height of the fluid in each of these tanks based the lowest outflow point. Each stage of the analysis is considered independently with the tank spilling from its originally filled level as specified in the Loadcase. You can select an option to allow the tank to refill should the lowest outflow point be immersed below the external seawater level. View a complete set of results for each room for Equilibrium analysis, and for each room for all heel angles in the case of a Large Angle Stability analysis. Results include the centroid and mass of cargo (in the case of a filled tank), buoyancy (in the case of damaged rooms or permanently flooded spaces) and water on deck (in the case of spaces defined as having water on deck applied).
This option is available for Large Angle Stability analysis only. Following guidance from MCA (Maritime and Coastguard Agency, UK) The GZ curve is calculated as normal then for each heel angle the volume of water on deck is calculated and its effect on righting centre of gravity and righting moment calculated (the vessel is not rebalanced to the increased displacement and change of CG). These data are reported as a modified GZ curve and stability criteria may be calculated using this modified GZ curve if required).
When reporting directly to MS Word the is the option of specifying a MS Word template document to be used. This enables customisation of the data, tables and graphs which are included in the report for each analysis type.
A recent addition to Stability is the ability to generate a report from a database containing previously calculated results, this means that the report template can be modified and the report regenerated very quickly (using the pre-calculated results in the database)
A final option for fully-customisable reports is the ability to drive Stability from a MS Word (or MS Excel) VBA (Visual Basic for Applications) Using this approach you can use VBA and the Stability automation interface to run specific analyses then extract and format the data required in your report
Results from all MAXSURF Stability analyses can now be automatically stored in a SQL database. At the click of a button you can restore the results, saving time previously spent re-analysing. All settings related to the analysis run are also stored and reloaded, making it easy to review parameter settings and either reproduce results or recalculate them for slightly varied parameters. This greatly facilitates report generation by allowing you to select which analyses should be included in the report and in what order. Modify the report settings (table format, report templates) and regenerate the report in seconds using the results stored in the SQL database. Turn on options to auto-load the most recent results when you open a model to continue where you left off the last time you edited the model, or to reload results as you toggle between current Loadcases and Damage Cases.
Use these powerful functions to quickly and easily access any set of results and analysis settings from the design process without having to perform time consuming reanalyses, or re-enter analysis settings. A simple SQL database is used enabling expert users to interact with the results directly.
In theory only available disc space limits the number of analysis results that may be stored in the SQLdatabase, however access performance may deteriorate if too many sets of results are stored in the same database
MAXSURF Motions provides Hydrodynamic Motions and Seakeeping Analysis. It uses the trimmed MAXSURF NURBS model eliminating the need to prepare input or offset files. It will predict the motion and response of vessels in a range of sea states at user-defined headings and speeds. Naval Architects are able to optimize the vessel design with an in-depth understanding of Response Amplitude Operators (RAOs), accelerations, and Motion Sickness Incidence at any location on the vessel.
Data is displayed simultaneously in graphical and tabular form and is automatically updated in real time when changes are made as the analysis progresses. Data can be copied to spreadsheets and other applications for presentation purposes or further analysis such as calculating the probability of slamming and propeller emergence in heavy seas.
During the quick set-up of the analysis, you can specify the wave spectrum (from a selection of five in the menu), heading, vessel speed, and other mass distribution parameters such as VCG of the vessel and Gyradii. RAOs are computed, as well as the added resistance, significant absolute and relative motions, velocities, and accelerations of the vessel in the specified sea spectrum. Motion, velocity, and acceleration and Motion Sickness Incidence (MSI) may also be computed for any position on the vessel.
Both Strip Theory and 3D Radiation-Diffraction Panel Methods are available. Strip theory provides fast calculation of heave, pitch, and roll response for hull shapes with L/B (length-beam ratio) greater than 4. The panel method can be used for any vessel shape and provides full six degrees of freedom response calculations.
The linear strip theory method is based on the work of Salvesen et al, and it is used to calculate the coupled heave and pitch response of the vessel. The roll response is calculated using linear roll damping theory. In addition to graphical and tabular output of numerical results data. The strip theory computations have been found to be most reliable from head seas (180 deg) to bow-quartering seas (135 and 215 deg). Strip theory calculations for following seas are less accurate and should be validated by other means, since the motions become much more nonlinear.
The panel method is a first-order diffraction/radiation hydrodynamic analysis in which a constant panel based boundary element method (BEM) is used. The panel method generates its analysis elements based on the MAXSURF NURBS surface model. The panel method generates Response Amplitude Operators (RAOs) for all six degrees of freedom: surge, sway, heave, roll, pitch and yaw. The panel method is valid for a very large range of geometries but is restricted to zero forward speed. In addition to outputting RAOs, the panel method output also includes hydrodynamic added mass and damping, first order wave exciting forces and moments, mean drift forces and moments, and pressure on the vessel wetted surface.
If you click the screen shot shown below and review it closely, you will gain a better understanding of the extent of insights gained from a MAXSURF Motions analysis. For example, you can freeze the animation of the vessel encountering a wave at any point and in the lower left corner of the screen, know the precise data point in the applicable results table. This data can easily be analyzed further in an Excel spreadsheet.
The RAO is a transfer function (similar to the response curve of an electronic filter) describes how the response of the vessel varies with frequency. These are normally non-dimensionalised with wave height
or wave slope. Typical heave and pitch RAOs are shown below:
The probabilistic damage analysis now provides the option of computing the vessel hydrostatics at the final equilibrium damaged waterline for each damage and loadcase combination. The results of these equilibrium analyses are shown in the new Probabilistic Damage Equilibrium results table. You may use the Display Data Format dialog to select which columns are displayed; in addition to the standard Equilibrium analysis results you can also select to display the minimum freeboard of key lines and key points. The rows in this table have a 1:1 correspondence with the rows in the Probabilistic Damage results table.
Support lifecycle
Bentley Systems has made changes to the support lifecycle of desktop applications. One of the key changes is that major versions of Maxsurf will be supported with critical fixes for at least five years, although users are still encouraged to update to each new version to benefit from new features that are added to Maxsurf. These changes are detailed on the following web page: -lifecycle-policy/