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[Journal Papers]

An Integrated Workflow for Rapid Structural and Hydrodynamic Analysis of Ships and Offshore Structures

  • midas NFX
  • Intermediate level
  • 16 downloads
  • 2015.06.10

This project is presented during the COMPIT 2015 Conference by Mr. Zagkas and Mr. Spanos, SimFWD. It is republished here under the authors’ permission For details, please download the original article here

Analysis Objective

Investigate the behavior of a 70t bollard-pull tugboat, imposed into hydrodynamic loads and lastly into a collision with part of an offshore installation.

Analysis Type
CFD analysis
Linear static analysis
Explicit dynamic analysis
Geometric Modelling

The hull geometry was generated from CAD software. It is then imported to midas NFX for further simplification and modification. The fluid domain is modeled as a rectangular solid with specified dimensions based on the model particulars and the requested analysis. The size of the air domain has a breadth of 30 m, a length of 110 m and has 10.1 m height.

Hull surfaces imported and converted to B-Rep solid

Hull surfaces imported and converted to B-Rep solid

Fluid domain is created as rectangle solid

Fluid domain

Finite Element Modeling

The finest mesh quality was achieved, after testing a number of mesh sizes combined with the corresponding edge size, and was finally obtained for mesh size 0.124 m and edge size of 0.62 m.

Fluid domain meshing; sea and air

Fluid domain meshing; sea and air

For structural modeling of the hull, software BVB CAFE, which is a dedicated for rapid structural modeling of ships, is used. (original paper for integration detail). Then the created model is imported to midas NFX through Nastran data file for mesh refinement and further analysis.

CAFE model directly imported into MIDAS NFX

CAFE model directly imported into MIDAS NFX

Analysis Results

CFD results
CFD analysis was performed to get the pressure distribution on the aft part of the tug, which were used an input to the structural model solution. The results are shown below:

First step pressure distribution

First step pressure distribution

Level set deformation

Level set deformation

Linear Static Results
Using the pressure loads calculated in CFD analysis, we calculated the total translation, Von Misses stress and overall safety factor through linear static analysis.

FEM Linear Static Results

FEM Linear Static Results

Explicit Dynamic Analysis Results
Collision between the aft part of the structure and a Pillar of an offshore structure was analyzed.

Collision analysis set-up and results

Collision analysis set-up and results


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