Ramm

Arc Length Algorithm Using Ramm's Approach

The Ramm's version of arc length algorithm is implemented. This solver can only be used in solving static problems.

Syntax

solver Ramm (1)
# (1) int, unique solver tag

The step size in an arc-length analysis is now the arc length. One can use the following to control stepping strategy.

set ini_step_size (1)
set min_step_size (1)
set max_step_size (1)
# (1) double, step size (arc length)

set fixed_step_size (1)
# (1) bool, flag to indicate if to fix the arc length

Remarks

1. A proper arc length shall be manually input to achieve an efficient analysis.

2. Often the arc length is allowed to change depending on the smoothness of the turning point.

3. The computation of determinant is involved. A proper matrix storage scheme shall be activated. For dense matrix storage, please use asymmetric schemes by set symm_mat false. For sparse solvers, please use MUMPS only.

4. If the arc length is not fixed, a positive minimum/maximum arc length (step size) will kick in to prevent the arc length from being too small/large.

5. Any non-positive values for the minimum/maximum arc length will be ignored.