# CONN3

Connector ElementCONN3 lets you define the motion at a reference NLFE grid as the weighted average of the motions at a set of other NLFE grids.

## Format

```
<CONN3
id = "integer"
gi1 = "integer"
wt1 = "real"
gi2 = "integer"
wt2 = "real"
...
...
gi = "integer"
conn = "string"
[graph = "integer"]/>
```

## Attributes

`id`- Unique identification number.
`gi1`,`gi2`, …- Grid identification numbers for the first, second, …, grids
`gi`- The reference grid identification number.
`wt1`,`wt2`, …- Weight values for the first, second, …, grids.
`conn`- String containing at most 12 characters that describe the connection between the coordinates. 4
`graph`- Post-processing flag. Use this flag to control how this element is displayed in the animation H3D. Default for graph is 0. 6

## Example

The example demonstrates the definition of a CONN3 element.

`<CONN3 id="100" gi1="1" wt1="1." gi2="18" wt2="1." gj="35" conn="TTTTTTTTTTTT"/>`

## Comments

- This type of element is used to connect the motion at a reference grid (Grid J) as the weighted average of the motions at a set of other grid points (Grid I's). Up to 300 grids (Grid I's) may be defines. Each connector element of type CONN3 has a unique identification number with respect to other connector elements of the same type.
- If any of the weights associated with a grid are not specified, then that weight is assigned a value of 1.
- Grid J (reference grid) is required to have full
12 generalized coordinates associated with it. CONN3
establishes up to 12 kinematic relationships of one or more Grid I's
coordinates with respect to Grid J coordinates:
(1) $$\begin{array}{l}{\displaystyle \sum _{k=1}^{n}({w}_{k}{r}_{I}^{k}})/{\displaystyle \sum _{k=1}^{n}{w}_{k}}={r}_{J}+{c}_{0}^{1}*r{x}_{J}+{c}_{0}^{2}*r{y}_{J}+{c}_{0}^{3}*r{z}_{J}\\ {\displaystyle \sum _{k=1}^{n}({w}_{k}r{x}_{I}^{k}})/{\displaystyle \sum _{k=1}^{n}{w}_{k}}={c}_{1}^{1}*r{x}_{J}+{c}_{1}^{2}*r{y}_{J}+{c}_{1}^{3}*r{z}_{J}\\ {\displaystyle \sum _{k=1}^{n}({w}_{k}r{y}_{I}^{k}})/{\displaystyle \sum _{k=1}^{n}{w}_{k}}={c}_{2}^{1}*r{x}_{J}+{c}_{2}^{2}*r{y}_{J}+{c}_{2}^{3}*r{z}_{J}\\ {\displaystyle \sum _{k=1}^{n}({w}_{k}r{z}_{I}^{k}})/{\displaystyle \sum _{k=1}^{n}{w}_{k}}={c}_{3}^{1}*r{x}_{J}+{c}_{3}^{2}*r{y}_{J}+{c}_{3}^{3}*r{z}_{J}\end{array}$$The constant coefficients in the equations above are automatically computed by MotionSolve based on the model positions of Grid I's and Grid J.

- The letter 'T' in attribute
`conn`indicates the particular kinematic relationship that will be imposed by MotionSolve at all times during the simulation. The attribute`conn`can have up to 12 'T' (True) or 'F' (False) characters. For example, if`conn`="TTTFFFFFFFFF", the first three conditions in the previous comment will be imposed and the rest of the conditions will not be imposed by MotionSolve. - The default for the attribute
`conn`is "FFFFFFFFFFFF". Further,`conn`="TTT" is equivalent to`conn`="TTTFFFFFFFFF". If the number of characters in the attribute`conn`is more than the number of generalized coordinates of any of the Grid I's, any character which does not have corresponding coordinates in any of Grid I will be ignored. - The
`graph`attribute controls how this connector element is displayed in the animation H3D:`graph`="0" implies the CONN2 element is not represented in the H3D`graph`="1" impliesthat a line connecting the two nodes will be displayed for this element.