3.3.8. RiksSolver

The RiksSolver (arc-length method) follows equilibrium paths through limit points by augmenting the Newton–Raphson iterations with an additional constraint on arc-length. It adapts step size to balance convergence effort.

3.3.8.1. Overview

Solver type: RiksSolver

Method: arc-length with predictor–corrector iterations
Control: maintains a constraint on combined displacement and load increments
Step size: adapts factor per cycle toward an optimal iteration count
Termination: stops when lam > maxLam or a cycle cap is reached

3.3.8.2. Parameters

3.3.8.2.1. Mandatory Parameters

Parameter	Description
`type`	Must be set to `"RiksSolver"`

3.3.8.2.2. Optional Parameters

Parameter	Description
`tol`	Convergence tolerance (default: `1.0e-5`)
`optiter`	Target iterations per step to tune step factor (default: `5`)
`iterMax`	Maximum iterations per cycle (default: `10`)
`fixedStep`	Use fixed step size when `true` (default: `false`)
`maxFactor`	Maximum cumulative factor to prevent step shrinkage (default: `1.0e20`)
`maxLam`	Maximum load factor (default: `1.0e20`)

3.3.8.3. Examples

examples/ch04/ShallowtrussRiks.pro

3.3.8.4. See Also

../solvers
Elements: Truss, ../elements/smallstraincontinuum