NOLIN2

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

(1)

P_{i} (t) = S \cdot X_{j} (t) \cdot X_{k} (t)

Where, $X_{j} (t)$ and $X_{k} (t)$ can be either displacement or velocity at points GJ and GK, respectively, in the directions of CJ and CK, respectively.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
NOLIN2	`SID`	`GI`	`CI`	`S`	`GJ`	`CJ`	`GK`	`CK`

Example

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
NOLIN2	14	2	1	2.9	2	1	2

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`, `GK`	Grid or scalar point identification number. No default (Integer > 0)
`CJ`, `CK`	Component number for `GJ, GK` according to the following table:

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

Comments

Nonlinear loads must be selected by the Subcase Information data selector NONLINEAR.
Nonlinear loads may not be referenced on a DLOAD entry.
All degrees-of-freedom referenced on NOLIN2 entries must be members of the solution set.
GI-CI, GJ-CJ and GK-CK may be the same degree-of-freedom.
Nonlinear loads may be a function of displacement (X = u) or velocity $(X = \dot{u})$ . Velocities are denoted by a component number 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)
${\dot{u}}_{t} = \frac{u_{t} - u_{t - 1}}{Δ t}$
Where, $Δ t$ is the time step interval and u_t-1 is the displacement of GJ-CJ or GK-CK for the previous time step.
The time step algorithm in transient solution sequences may loose unconditional stability when this load entry is used. In most practical cases, the time step size chosen to reach a certain accuracy is below the stability limit. It is recommended to decrease the time step if results diverge.