Learn About Our Structural Analysis Software
Viking Systems International uses state-of-the-art structural modeling and analysis software tools such as Femap, Nastran, Sesam, LS-DYNA, and Classification Society program in combination with our proprietary software, SAGA, for modeling, loading, and evaluating ship structures. Below, you can read about the main features of SAGA and how we apply the program to reliably and rapidly model, load, balance, and evaluate FEA models against classification society structural codes from ABS, DNV, BV, Lloyds, API, AISC, and other rules.
Why Viking Uses SAGA
We have developed our structural design software procedures around SAGA to obtain a reliable, repeatable, and cost-effective method that ensures our clients receive consistent high-quality work from our departments. We have achieved a flexible structural modeling, loading, and evaluation tool interaction with other efficient, industry-accepted software, such as modeling software (FEMAP, Ansys, SACS), FEA solvers (Nastran, Sestra, LS-Dyna), stability programs (Hecsalv), and hydrodynamic programs (WADAM, Wasim, Aqwa, Wajak). The results are available in the virtual reality modeling language (VRML) format that is viewable in web browsers.
The SAGA computer program has been applied to ships and offshore structures fabricated from steel, aluminum, and composite construction materials, using processes like the following:
- Finite Element Model creation and mesh-checking
- Translation between Femap, Nastran, Nauticus, Sesam, Ansys, SACS, SafeHull, Veristar, and Hecsalv
- Application of loads from rules or hydrodynamic analysis
- Balancing of loads in case of a floating application
- Assessment of yielding, buckling, fatigue, and vibration modes
- Application of structural criteria from classification society codes, API, and AISC
SAGA gives our teams the tools they need to focus on solving structural problems, ensuring a design is adequate and optimal. SAGA allows for the following:
- Assessment against any number of rules and any number of load cases, with plots showing the maximum response for each structure under design loads
- Calculation of paint areas, weld lengths, weights, centers of gravity, and etc.
- Plotting of results into typical structure groups for clearer results, allowing easy access to data essential to updating structural drawings and creating reports
3D Finite Element Modeling (FEM)
SAGA is used to rapidly create ship finite element models via import of CAD transverse section offset data in formats used by surface modeling tools. The file formats supported include Autocad .dxf, GHS .gf1, and HECSALV .hul files. The system supports the assembly of models created by several team members using SAGA in combination with a finite element modeler, such as FEMAP, ABAQUS, or ANSYS. This method supports a parametric assessment of a number of structural configurations under consideration. Detailed local models can be made from the global model, using features like nodal section insertion and beam shapes-to-plate data extraction. The local models are loaded by nodal deflections and rotations, accelerations, and pressure loading.
Loading Analysis, Balancing, and Interfaces to External Programs
SAGA carries out fine element grouping to support naval architecture loading groups throughout the vessel. The loading groups include the external hull, tanks, deck areas, engine room, and other user-defined groups depending on the analysis requirements. The hull group can be exported in Nastran format for loading by external programs, such as WASIM, WADAM, LAMP, or by SAGA using built-in classification society rules. After the loads have been added, SAGA is used to either inertia balance or position balance the model to eliminate boundary condition influence.
Evaluation of Results
SAGA reads stresses from Nastran and from DNV's Sestra program for assessment against the yielding and buckling requirements of classification societies ABS, BV, and DNV for ships and offshore structures. SAGA performs advanced post-processing of results by the establishment of structural failure regions in combination with the material, property, deflection, and stress data from the finite element model. SAGA is capable of using classification society rules from ABS, DNV, BV, and Lloyds; additional custom code checks are easily programmed by the user via spreadsheet interface.
Code Compliance Check
Viking Systems International’s SAGA program is constantly at work on ships and offshore structures, providing our teams with design and assessment capabilities on all types of structures. SAGA is used for structural projects of all types of ships, including:
- FPSO, FSO and FLNG vessels
- Jackup offshore installations
- Navy and Coast Guard vessels
- High-Speed Light Craft
- Ships and Barges
- Cruise ships, Yachts and Entertainment Vessels
SAGA's built-in code checking capabilities include the industry standards published by regulatory bodies including the structural rules by classification societies:
- ABS FPI Rules
- ABS MODU Rules
- ABS HSNC High-Speed Naval Craft
- ABS Naval Vessel Rules
- BV Parts A-D and NI593
- API RP 2A
- DNV OS-C101
- DNV RP-C201, RP-C203, RP-C205, RP-C206
- ABS SFA Spectral Fatigue
- DNV FMS Notation Stochastic Fatigue
Viking Systems SAGA program prepares results for our users and clients using a Virtual Reality Modeling Language (VRML) format viewable in standard web browsers and other programs that read VRML (for example, Rhino). The result files are available for use by information technology interested clients wishing to see the results in interactive 3D, rather than simply as shown in reports.
Team Spirit shows in Naming of Our Computer Programs
Viking Systems’ computer programs and team spirit are named from Nordic mythology in keeping with our Viking traditions from over a thousand years ago:
- SAGA stands for Structural Assessment Graphical Application and is a computerized tale of “structural events” that are created, assessed and safeguarded for current and future learning just like the Viking era Sagas that are preserved to this day,
- ODIN (Optimum Design Integration Network) is named after the Viking leader Odin who sends out a pair of ravens Hugin (from Old Norse "thought") and Munin (Old Norse "mind") all over the world to gather information – in our case on our many structural computing solutions created throughout our network of computers and people involved,
- THOR, the son of Odin and Fyorgyn is the most powerful of all in taking action, of going beyond boundaries, and of team leading. Each of our Viking Systems team members, like Thor embody great strength of character, indispensable leadership qualities, and are also strong team players – true qualities for past as well as us modern day “Vikings”.