### 14.3.1. Interactions - Euler/Lagrange (3D) - Type

Select the type of automation you want to use for the Euler-Lagrange/Shell interaction definition.

Fully Auto

  The Fully Auto option will fully automate the set up of the Euler-Lagrange/Shell coupling. All structural Parts will be coupled to the Eulerian Parts in the model, and all shell Parts in the model will be thickened in such a way that they will fit the region of the Euler mesh they initial reside in. For each shell Part, the fully automatic method will compute the largest element diagonal of all Euler elements the shell part initially resides in. The artificial coupling thickness is then taken as 1.5 times the value of the largest element diagonal and is applied as a centered thickening. This will guarantee that thickened shell parts at the beginning of the analysis at least fully cover the Euler elements the shell resides in, which is a prerequisite for the coupling algorithm to function correctly. In cases where a large mesh grading is applied, the initial shell thickness might not be large enough when the shell Part moves into an Euler region with larger size elements and the Euler elements are not fully covered anymore. The automatic coupling method will notify you at the beginning of the analysis if such a risk exists and you can then decide to use a smaller grading of the Euler mesh if required. This typical warning message is shown below:

  Aside from Part selection and automatic shell thickening, the fully automatic option also checks the orientation of the shell normals within a single shell part, and also the orientation of the normals of different shell parts at a (T)-joint. Based upon this information, the automatic method will create a consistent closed-coupling surface in a way similar to that you must do in a manual manner in cases where inconsistent normal directions would cause problems. The manual options available are reversal of normals under the Group option and the removal of Parts in the join normal calculation.

  Some typical examples:

Semi Auto

  Semi Auto is similar to the Fully Auto option. The only difference is that for the Semi Auto option you must manually select the structural parts for interaction with the Euler Parts. The artificial coupling thickness of the selected shell Parts again is computed fully automatically.

Manual

  When Manual is selected, you must define the complete coupling manually by selecting the structural Parts for Interaction, defining the artificial shell coupling thickness, and verifying that the coupling surface is a consistent closed surface.

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