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Menu: Elements

This is the basic menu for editing elements.
We have to remember that an element is a triangle in the space. In order to view the elements on the screen, we have to press elements button BotoElement on right hand side of the top toolbar.

 

Automatic generation

When we generate a mesh via the menu File | New | Mesh, all we get is a mesh of bars (could be cables in a real structure), but not a surface. WinTess3 has this menu to obtain the membrane surface that simulates the wire mesh. It presents two submenus:

  • Triangular mesh
    It is used to generate elements when the mesh is triangular and already have the triangles that are going to be elements of the membrane. The process is faster since you don’t have to search other closed polygons and decompose them to triangles.
  • Orher mesh
    When we use another type of mesh (square, rectangular, radial,…), the process of generation of triangles is longer and more complicated, especially in the perimeter, since the program must find closed polygons (usually quadrilaterals) and decompose them into triangles.

Once the automatic generation of elements is done, they appear on the screen. It is the time to observe that there is no errors, and if there is, they need to be corrected. The most common failures in this automatic generation of elements are:

  1. There is no triangular areas.
    It is as if there are large holes in the membrane. We must create the missing triangles manually to fill all the gaps.
  2. Some elements are reversed.
    They appear with inverted color: yellow at the top and blue at the bottom. We will have to invert these triangles so that all membrane is uniform.

In the case of non-triangular mesh, WinTess3 creates two diagonal bars in every quadrilateral in order to avoid deformations that transform a square into a diamond without elongation of the sides which would generate tension equal to zero while the distortion could be big. If the user does not want to use them, the diagonals can be deleted any time via the menu Bars| Delete diagonals.


Refine

When we work with a mesh of few elements which helps facilitating computational tasks, it is sometimes necessary to have more elements to obtain a good pattern as a sparse mesh is too faceted or little smooth for create a good pattern. For this reason WinTess3 has this menu which lets you break down each element into four others using the midpoints of the three sides.

Refinado1

Mesh before refine

Refinado2

Mesh after refine

The refining process is quite complicated, since the following aspects must be taken into account:

  • initial nodes (which exist before refining) are kept in their position after refining.
  • Each side of the triangle (element) decomposes into two by creating a new node. This node is not simply the mid-point between of the side in question, but it must be another very close to this point, but located on a smooth surface curve passing through initial nodes.
  • Edge elements will generate new nodes that will not be directly on the edge, but it will make the bolt ropes smoother (with double points).
    IMPORTANT NOTE: This third aspect is still under development. (March 2011)

Create new element

If we want to create a new element (triangle), we use this menu. The mouse cursor changes to selection finger and we need to select three consecutive nodes counterclockwise. As soon as we select the third node, the newly created element is displayed and the cursor remains in its selection position ready to create another new element. When we finish the task of creation of elements, click the right mouse button, as it finalizes any action.
If any of the elements created appears inverted (yellow top), it should be reversed so that it is in the correct position.


EditConstruccioPetit

This menu is still in the development phase. (March 2011)


Initial data

The program displays a table of initial values of the elements:

Elem: Element number
N1,N2,N3: Nodes that define the element
Ax,Ay,Az,At: Area of the element as projected on YZ, ZX, XY planes, respectively and finally the total area. The projected areas have a sign or direction because the elements have directionality (blue or yellow face)
Weight: Weight of the element (it is assumed that it is already materialized and is a type of membrane in particular).
Wind:
Slope: Angle of inclination of the surface of the element. If it is horizontal, it has a value of 0° and if vertical, it is 90°


Final dataConstruccioPetit

This menu is still in the development phase. (March 2011)


LoadsConstruccioPetit

This menu is still in the development phase. (March 2011)


Reverse

We use this menu to reverse (change side) those elements that for some reason are inverted (the yellow face is upwards and the blue side is down). The cursor changes to selection finger, we select those elements you want to reverse, one by one or through a window. Finally using the right button of the mouse, we complete the selection and a message of confirmation for reverse action is displayed. The program is still in this menu until you press the right button of the mouse on a blank area to finish (as usual).


Delete graphically

We use this menu to delete elements that need to be removed for some reason. The cursor changes to selection finger, then we select the elements we want to delete, one by one or through a window. Finally using the right button of the mouse completes the selection and a message of confirmation of the delete is displayed. The program is still in this menu until we press the right button of the mouse on a blank area to finish (as usual).


Delete all

By means of a confirmation message, WinTess3 asks us if we want to delete all items. If the answer is yes they are all deleted. This action usually takes place before automatic generation of new elements since there have been changes in the structure: nodes, bars,…


 Locate an element

Many times, we need know where a certain element is, to evaluate our work, to edit, etc. When the structure has many elements, this can't be done at first glance by looking at the screen. WinTess3 provides this tool through the window seen on the right. As soon as we enter the number of the element we want to locate, the element immediately appears on display in red color.
element-locateelemLocalitzat