# Define Preload, Offset and Scale

The Preload/Offset/Scale tab displays the force characteristics of your bushing as you see in the following figure:
Note: The Preload default value = 0; The Offset default value = 0; and the Scale default value = 1.0. The same holds true for both translational and rotational directions.
2. Enter the Preload Force X, Y and Z values as a real value. Positive preload (Pk) values act to attract the two bodies.
3. Enter the Preload Torque X, Y and Z values as a real value. Positive preload torque values act clockwise about the given axis (that is, x, y or z) on body 1 and counter-clockwise on body 2.
4. Enter the Offsets Disp X, Y and Z values as a real value. Displacement offsets (Qk) are subtracted from the actual displacement of body 1 with respect to body 2.
5. Enter the Offsets Angle X, Y and Z values as a real value. Angle offsets are subtracted from the actual angular displacement.
6. Enter the Scales Disp X, Y and Z values as a positive, real value. The displacement scale (Hk) scales both the input displacement and velocity, but not the displacement offset. The default value is one (1).
7. Enter the Scales Angle X, Y an Z values as a positive, real value. The displacement scale (Hk) scales both the input displacement and velocity, but not the displacement offset. The default value is one (1).
8. Enter the Scales Force X, Y and Z values and Torque X, Y Z value as positive, real values. Enter a positive, real value. The force scale (Vk) scales the force function, but not the preload. The default value is one (1).
The following figure shows the effect of preload and offset on a bushing:
The bushing force for the Kth direction (x, y, z, ax, ay, az) is defined by a function:(1)
${F}_{k}=-{G}_{k}\left({q}_{k},{\stackrel{˙}{q}}_{k},{x}_{k},t\right)$
Where,
${F}_{k}$
Force in the kth direction
${G}_{k}\left({d}_{k},{\stackrel{˙}{d}}_{k},{x}_{k},t\right)$
Force function in the kth direction
${d}_{k}$
Displacement input in the kth direction
${\stackrel{˙}{d}}_{k}$
Velocity input in the kth direction
${x}_{k}$
Array of internal state (that is, hysteresis) in the kth direction
$t$
Time

The displacement offset Qk and the displacement scale Hk modify the displacement and velocity to compute new inputs to function G as follows:

${q}_{k}={H}_{k}\cdot {d}_{k}-{Q}_{k}$ is the scaled, offset displacement.

${\stackrel{˙}{q}}_{k}={H}_{k}\cdot {d}_{k}$ is the scaled velocity.

So force is then computed using the modified inputs ${q}_{k}$ and ${\stackrel{˙}{q}}_{k}$ :(2)
${F}_{k}=-{G}_{k}\left({q}_{k},{\stackrel{˙}{q}}_{k},{x}_{k},t\right)$
Finally, the force/torque preload Pk and force/torque scale Vk modify the output so the force computation is:(3)
${F}_{k}={P}_{k}-{V}_{k}\cdot {G}_{k}\left({q}_{k},{\stackrel{˙}{q}}_{k},{x}_{k},t\right)$