This tool can be used to mesh a panel that was initially created with large triangular and quadrilateral plate elements. It can also be used to refine an existing plate mesh or specific parts of it.
Note that this tool replaces the plate elements being meshed (along with their nodes), and so any node loads, plate loads, restraints or constraints previously applied to the affected nodes and plates will be deleted. It is therefore recommended that you finalise the use of this tool before you apply your restraints, constraints and loads in order to avoid having to re-apply them.
In order to mesh a panel consisting of large unmeshed plate elements, you should select the elements in the panel, right-click and then select "Mesh Tools" => "Mesh Plates (Advanced)" from the popup menu that appears.
The form that appears next allows you to adjust the various settings that control the meshing.
The mesh sizes panel lets you control the size of the elements to be generated in the various parts of the panels being meshed. Each of the mesh size settings can be specified as a length or as a percentage of the maximum segment length. The maximum segment length (5m in this case) is the longest segment in the panel boundary and is determined automatically based on the members you have selected.
The "Default mesh size" is used for any of the settings below it that aren't ticked.
The "Boundary" setting applies to the elements to be generated around the external boundary of each panel being meshed.
The "Sub-panels", "Openings" and "Hard lines" settings are not used in this mesh tool.
If any in-plane nodes are to be included in the mesh then you should tick the "Include in-plane nodes" option and optionally tick the "Nodes" box and set the mesh size for the elements to be generated around them.
The "Internal plates" setting applies to the elements to be generated away from the boundary and away from any in-plane nodes.
Note that in order to achieve well conditioned elements while preserving compatibility with the surrounding elements, the requested element sizes may not always be achievable.
By default, the mesh tool will generate a mixture of quadrilateral and triangular elements, however you can limit it to just one type by unticking either one.
Invalid elements generally occur when an element has an aspect ratio greater than 4:1 or an internal angle greater than 135 degrees. If you tick the "Attempt to correct invalid elements" option then it will re-arrange the mesh and/or split problematic elements into two or three in an attempt to correct them.
Keep in mind that the "Attempt to correct invalid elements" option is not always successful and so occasionally you may get a warning about the mesh not being generated due to invalid elements. In such cases you could either change some of the mesh settings or tick the "Allow invalid elements" option and then once the mesh is generated use the "Find" tool to locate the invalid elements and attempt to correct them manually.
During the meshing process, if two nodes finish up very close to each other and you have ticked the "Merge nodes that finish together" option then the close nodes will be merged into one.
Filters can be automatically generated during the meshing process so that the various components of the finished mesh can be easily isolated and selected. If you leave the "Filter name" field blank then each time you mesh a new panel it will create a filter for that panel called "Panels n", where n is the panel number. If you prefer to define your own filter name then you can enter it into the "Filter name" field.
In order to prevent the mesh tool from generating an excessive number of elements, especially if you are unsure of the mesh size settings to use, the "Maximum elements for this panel" setting allows you to set an upper limit that will cause the mesh tool to stop if it is exceeded.
There is still an upper limit of 32765 nodes, members and plates currently in SPACE GASS and so the "Maximum elements for this panel" setting helps you to stay within this limit for your model as a whole. It is planned for this upper limit to be removed in the next major release of SPACE GASS.
The plate properties and material panels let you set the thickness, offset, type and material of the elements to be generated.
In the shared edges panel you can elect to "Preserve existing plate edges". This applies when a panel being meshed has a common boundary with another panel not being meshed. If you tick this option then the panel being meshed will generate elements along the common edge that match the elements in the other panel so that the two panels are properly connected. If you untick it then the panel being meshed will generate elements independently of the other panel and may result in the two panels not being connected properly. Generally you would untick the "Preserve existing plate edges" option only if the other panel has not yet been meshed.
The "Subdivide members" option controls whether the members you have drawn to define the meshed panel and its sub-panels, openings and internal walls are subdivided or not. If the members are intended to be a permanent part of the structural model then you would probably want them to be subdivided for proper connectivity with the generated plate elements, however if they are just acting as temporary "construction lines" then there would be no need to subdivide them.
As an example of how to set the "Preserve existing plate edges" option, consider the panel on the left below that is about to be meshed.
If the "Preserve existing plate edges" option is unticked then the following could occur. You can see that along the common edge there are some locations where a node exists partway along the side of an element. These nodes are not connected to the "Other" panel because elements only connect to other elements via their nodes and not along their edges.
If the "Preserve existing plate edges" option is ticked then you get a much better result with all the elements along the common edge properly connected as shown below.
However if the "Other" panel has not yet been meshed then you should untick the "Preserve..." option in order to avoid the following.
The numbering of nodes and plates being generated can be controlled to some extent via the "Start node" and "Start plate" settings. If you leave them blank then the next available numbers will be used.
In the following example, a panel created with three very coarse quadrilateral plate elements is to be meshed so that it is suitable for analysis.
After selecting all three elements, and then using a uniform mesh size of 1m, the panel is meshed as shown below.
If you wanted a finer mesh around the internal corner you could select the elements in that area, re-start the "Mesh plates (advanced)" tool and reduce the requested mesh size to obtain the following.
For further information about other plate mesh tools refer to "Mesh tools".