# NOLIN4

Bulk Data Entry Defines nonlinear transient forcing functions of the form.

(1)
${P}_{i}\left(t\right)=\left\{\begin{array}{cc}-S\cdot {\left[-{X}_{j}\left(t\right)\right]}^{A},& {X}_{j}\left(t\right)>0\\ 0,& {X}_{j}\left(t\right)\le 0\end{array}$

Where, ${X}_{j}\left(t\right)$ may be a displacement or a velocity at point GJ in the direction of CJ.

## Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
NOLIN4 SID GI CI S GJ CJ A

## Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
NOLIN4 2 4 6 2.0 101   16.3

## Definitions

Field Contents SI Unit Example
SID Nonlinear load set identification number.

No default (Integer > 0)

GI Grid or scalar point identification number at which nonlinear load is to be applied.

No default (Integer > 0)

CI Component number for GI.

No default (1 ≤ Integer ≤ 6; blank or 0, if GI is a scalar point)

S Scale factor.

No default (Real)

GJ Grid or scalar point identification number.

No default (Integer > 0)

CJ Component number for GJ, GK according to the following table.
A Exponent of the forcing function.

No default (Real)

Type Displacement Velocity
Grid 1 ≤ Integer ≤ 6 11 ≤ Integer ≤ 16
Scalar Blank or 0 Integer = 10

4. Nonlinear loads may be a function of displacement $\left({X}_{j}={u}_{j}\right)$ or velocity $\left({X}_{j}={\stackrel{˙}{u}}_{j}\right)$ . Velocities are denoted by components ten greater than the actual component number; that is the component 11 indicates velocity in the 1 component direction. The velocity is determined by:(2)
${\stackrel{˙}{u}}_{j,t}=\frac{{u}_{j,t}-{u}_{j,t-1}}{\text{Δ}t}$
$\Delta t$
${u}_{j,t-1}$
5. Use a NOLIN3 entry for the positive range of ${X}_{j}\left(t\right)$ .