# Spline Stiffness Block

Spline stiffness blocks store the static stiffness properties of a bushing. The data
is stored in a table of monotonically increasing deflections versus forces. If the
direction block selects the spline stiffness formulation for a given direction, for
example FZ, then the property file should contain a corresponding spline stiffness
block for that direction, such as `[SPLINE_STIFFNESS_FZ]`

.

The following table shows the parameters stored in spline stiffness blocks.

Abbreviations are [A] = angle dimension, [F] = force, [L] = length.

Parameter | Type | Dimension FX, FY, FZ | Dimension TX, TY, TZ |
---|---|---|---|

Displacement | real | [L] | [A] |

Force | real | [F] | [F][L] |

When the property file is read the deflection and force values are converted from the units of the property file to the units of the solver model.

The example below shows a typical spline block in the .gbs file
for the FY direction. The plot below that shows the shape of the
curve.

```
$---------------------------------------------------------- SPLINE_STIFFNESS_FY
[SPLINE_STIFFNESS_FY]
(SPLINE_DATA)
{ disp force }
-4.48 -1538.03776
-3.93 -933.55971
-3.38 -506.77016
-2.83 -227.72161
-2.28 -66.46656
-1.73 6.94249
-1.18 22.45304
-0.63 10.01259
-0.09 -0.43487
0.28 8.16256
0.83 66.78761
1.38 206.90616
1.93 458.46571
2.48 851.41376
3.03 1415.69781
3.58 2181.26536
4.47 3922.99269
```