# Modifying domains

In the AXISVM domains can be arbitrary spatial planar components. Their contour lines can be adjusted freely. The upcoming lines discuss that what possibilities are given to define or modify different types of shell elements.

## Domain#

When defining a domain in the following window can the options be set. Here the thickness and eccentricity as geometrical properties and the material of course as a material property can be set.

The next setting which is quite important in calculation point of view is the applied finite element type. Basically there are three possibilities to set: membrane, plate and shell.

In the next picture inner force vectors of membrane elements are drawn with blue. As it can be seen clear, membranes can only take internal forces in the direction of their plane. The next, red vector set is ordered to plate elements. As it is consistent, plates can only take internal forces perpendicular to their plane.

The third type of possible finite elements is the shell. In 3D models, all domains (planar components) should be defined as shell elements, since this elements can contain all internal forces. In spatial models, it is hardly possible to prevent that other (minimal) forces occur.

## Change domain contour#

After activating the function “Change domain contour” the chosen domain outline will be selected. By selecting a new outline, the domain contour can be redefined. It should be noticed that the largest closed outline selected will be used as new domain contour. If the domain has to be downsized, the selection of the “excess” area needs to be removed.

The command’s affect can be seen in the picture above. After selecting the domain and setting a spline which does not cut the contour of the selected area, it will result no affects. The next picture shows an example.

In this kind of formation the command is declined, it will not create an autonomic partial domain inside the original domain. This problem could be solved in the following way: select the spline and define it as a new domain.

In this picture in can be properly seen that due to defining the smaller domain the area of the bigger domain has decreased.

## Hole#

In the case when it is aimed to cut a partial area from the entire area, the cutting line can be given by the “Hole” option. Of coure, this opportunity also decreases the entire area and will be defined as a new domain type (hole) and will also get a serial number.

It is not possible to define a hole which extends over the original domain’s border. In this case the hole will fit to the edge of the domain.

## Cut a domain#

After activating the function “Cut a domain” one or more domain(s) can be selected. After confirming the selection with “OK” (selection toolbar) the cutting line(s) can be chosen. The cutting line has to run through the complete domain.

When domains are cut, the properties of the original domains are used for all resulting parts.

## Union of domains#

After activating the function “Union of domains” several domains can be selected. By confirming the selection with “OK” (selection toolbar) the chosen domains are merged.

If the properties of the domains are different, the domain that sets the properties of the new domain can be selected.

In case of this warning, by clicking “Yes” the domain can be selected, of which we want to keep the properties.

Source: http://www.ingware.com