Viking Systems uses state-of-the-art structural analysis software tools in combination with our proprietary software SAGA for modeling, loading and evaluation of 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 procedures around SAGA to obtain a reliable, repeatable, and cost-effective method to ensure our clients receive consistent high quality work by our ship and offshore structure modeling and engineering departments. We have achieved a flexible structural modeling, loading and evaluation tool interacting 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 virtual reality modeling language (VRML) format that are viewable in web browsers.

The SAGA computer program has been applied to ships and offshore structures fabricated from steel, aluminum, and composites construction materials, using our process of:

  • Finite Element Model creation and mesh checking

  • Translation between Femap, Nastran, Nauticus, Sesam, Ansys, SACS, SafeHull, Veristar, 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, AISC

SAGA gives our teams the tools to focus on solving the structural problems, ensuring a design is adequate and optimal:

  • 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, etc

  • Plotting of results into typical structure groups to easily understand the results and allowing easy access to the data needed to update structural drawings and create reports

3-D FEA Modeling

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 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 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

The grouping of finite elements is carried out by SAGA 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 establishment of structural failure regions in combination with material, property, deflection, and stress data from the finite element model.  SAGA is capable of using classification society rules from ABS, DNV, BV, Lloyds, and additional custom code checks are easily programmed by the user via spreadsheet interface.

Naming of Programs

Our proprietary programs are named from Nordic mythology as was Viking traditions 1000 years ago:

  • SAGA is a written tale of events (structural solutions created and safeguarded for future learning)

  • SAGA - Structural Assessment Graphical Application

  • ODIN is the leader who sends out his Ravens to listen and to gather information (submitted jobs finishing solutions throughout our network of computers and people)

  • ODIN - Optimum Design Integration Network  


SAGA Wave Loading and Balancing:

 

SAGA Global Modeling and Checking:

 

SAGA Buckling Assessment Model:

 

SAGA Groups for Loads Application:

 

 SAGA Imports Hydrodynamic Loads:

 

SAGA Loads Solved with Nastran:

 

 

SAGA Spectral Fatigue Assessment: