NOLIN3

Where, $X_j(t)$ may be a displacement or a velocity at point GJ in the direction of CJ.

Format

Example

Definitions

Comments

1. Nonlinear loads must be selected by the Subcase Information data selector NONLINEAR.
2. Nonlinear loads may not be referenced on a DLOAD entry.
3. All degrees-of-freedom referenced on NOLIN3 entries must be members of the solution set.
4. Nonlinear loads may be a function of displacement $\left(X_j=u_j\right)$ or velocity $\left(X_j={\dot{u}}_j\right)$ . 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:
   $${\dot{u}}_{j,t}=\frac{u_{j,t}-u_{j,t-1}}{\Delta t}$$
   Where,

   $\Delta t$

   Time step interval.

   $u_{j,t-1}$

   Displacement of GJ-CJ for the previous time step.

5. Use a NOLIN4 entry for the negative range of $X_j\left(t\right)$ .
6. 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.