To ensure that volumes of joined thickened shells do not overlap as the shells deform, the thickening algorithm needs some information on which shell parts should be considered joined when computing the outward normals for shell nodes in the thickening geometry calculations. By default all thickened shell parts are set as joined for the coupling calculation. If this is not appropriate, for example for a T-junction between two shell parts, you should remove the joins for the coupling calculation. It is important to note that these join settings are only used in the coupling calculation and do not affect the structural joins.
This is illustrated in the figure below. On the left, the two shell parts are joined for thickening calculations, and the resulting thickened shells define a closed volume. On the right, the two shell parts are not joined for thickening calculations, and the shell overlap is not satisfactory for coupling.
Shows all the shell parts that are coupled in Euler. When a part is selected in this list, all parts joined to it are displayed in the "Included parts for normal calculation" list.
Shows all shell parts that are joined to the shell part selected in "Select Part"
These two fields are used to add or remove parts from the normal calculation. For example, a model has shell parts "hull#1", "hull#2" and "composite", as shown in the image of the window at the top of the page. To include the normals between the first two parts, select "hull#1" in the left hand list, "hull#2" in the right hand list, and click the apply button.
If you select the review button, an HTML summary is opened that displays which shell parts have been included in the Euler coupling, the thickness and direction for these shell parts, and also the thickened shell joined matrix, that shows which shells are included in the normal calculation.
You can also view the thickened shells by switching on "Shell thickness" in the Plots panel, and choosing "Artificial Shell Coupling Thickness" in the Shell Thickness Settings panel.