The default transient scheme for the nonlinear system is the same as that used for linear elasticity: the Newmark Method. The semi-discretized equation of transient motion for the nonlinear system is given as:
(16–30) |
Note that the internal load is dependent on the current displacement at time . The linearized form of the previous equation can be obtained by the Newton-Raphson method resulting in following equation:
(16–31) |
where | |
= the residual vector | |
= the displacement increment | |
= the tangent stiffness matrix |
and
(16–32) |
(16–33) |
The same logic is extended to the Backward Euler scheme when used in conjunction with the Nonlinear Elasticity model.