Finite Element Model

In order to make for example, strength or vibration analysis of a selected part of a ship a Finite Element (FE) model has to be created. To do this manually involves a significant amount of work when the FE model is created to the expected accuracy and detail level.

Within AVEVA Marine there is support for FE model building by using the existing ship model whether it is an early stage design model or a fully detailed production model. Via a given set of rules and parameters an FE model is automatically created under user control.

An FE model differs significantly from the original ship model. It is supposed to capture the essential structural elements while disregarding insignificant components or features and describe them in a way suitable for analysis. The geometry of the FE model must form a connected 3D grid of points and lines. Properties from all kinds of components must be carried by the shell, beam and truss elements.

Depending on the size of the model and the type of analysis the simplification compared to the ship model may differ. Besides typical removal of small components such as drain holes, notches and cutouts, curved geometry must be represented by straight lines. The design intent and referential topology must be captured instead of just using the detailed physical shape of the model components.

Figure 6:1. Process Schema

Steps in AVEVA Marine:

1. Idealize Model

2. Create FE Model

3. Export FE Model

After structural modelling or Detailed Design of a panel, group of panels or block, finite element modelling can be run. First of all, the idealization step which is simplifying geometry for further processing and make geometry ready for intended element type representation (shell, beam and truss element) are run. In the second stage of the AVEVA FEM Interface, the final geometry is created according to the intended analysis and element selection. These geometrical entities together with their attributes like material, finite element type, real constants (area, thickness, moment of inertia ) are transferred to the FEA software and will be the basis for the final mesh consisting of nodes and elements with their corresponding shell, beam or truss element type.