Part VI
Verification
E. Algorithm and software checks · One-way support and rotational lift-off
A frame member is fixed at its root. Tip force is 10.0 N along x, and tip moment is 2.0 N·mm about z. A one-way support holds axial movement, and a lift-off support holds rotation. Both start active. Can both support states change in the same iteration?
This page preserves a recorded benchmark and its expected values. The dated run below is not a new run of the current product.
These recorded transitions and free-degree residuals do not establish general equilibrium or convergence for other models.
Support state check. The recorded test exercises nonlinear support state or assembled-loop behavior in its benchmark crate. It does not exercise desktop authoring.
The one-way support on a rotation is a numerical test of the iteration on a rotational degree of freedom. No such device exists in piping.
1.Inputs.
Illustrative values, taken from no standard and chosen so the arithmetic can be followed by hand. Most do not describe a real pipe; read them in any consistent set of units.
| Quantity | Symbol | Value |
|---|---|---|
| Tip axial force | Fx | 10.0 N |
| Tip moment about z | Mz | 2.0 N·mm |
| One-way support | — | Ux |
| Lift-off support | — | Rz |
| Initial one-way state | — | active |
| Initial lift-off state | — | active (in contact) |
2.Method.
On the first iteration both supports release. On the second iteration neither changes, so the loop has converged.
The reference for this group records the expected support states, changed-support counts and final residuals. It does not work out displacements or reactions, so none are tabulated here.
3.Results.
| Quantity | Expected |
|---|---|
| Changed supports, iteration 1 | 2 |
| Final changed-support count | 0 |
| Iteration count | 2 |
| Free-DOF force residual | 0.0 N |
| Free-DOF moment residual | 0.0 N·mm |
| Final free-DOF work residual | 0.0 N·mm |
| Final one-way state | inactive (released) |
| Final lift-off state | inactive (released) |
| Converged | true |
| Diagnostic | none |
The case record describes these checks:
- The solve converges in exactly 2 iterations: 2 supports change state on the first iteration and none on the last.
- Final states match the reference: both supports released. No diagnostics are raised.
- Over the last iteration both the rotation and the moment reaction change by more than zero, so the rotational terms are genuinely exercised.
- At the final iteration the out-of-balance force, moment and work at the free degrees of freedom are all exactly 0.0.
- The changes in displacement, rotation and reaction over the last iteration stay inside the recorded envelope for this group.
What it shows. Compares final support states, the iteration count, and force balance. It does not compare movements or reactions with a hand calculation.
Path exercised. The benchmark calls the solver’s components directly: elements, loads, frame solver and stress recovery. It does not go through the program’s own model-to-solve path.
Agreement. The loop counts as converged only when no support changes state between iterations. The changed-support count must reach exactly 0 within at most 4 iterations, with no relative or absolute allowance. At the final iteration, out-of-balance force, moment and work at free degrees of freedom must be 0.0. Changes in displacement, rotation and reaction over the last iteration must stay inside the recorded envelope. Long values are shown here to seven significant figures; the tests compare the full values in the record.
4.Recorded command.
This command belongs to the archived source at 462f66975d36cd10d5b8455193ada9517d28d353. Use a checkout of that exact revision. This edition did not run the command. The recorded result does not establish current product support.
git checkout --detach 462f66975d36cd10d5b8455193ada9517d28d353 cd projects/chirality-piping cargo test --manifest-path validation/benchmarks/nonlinear/Cargo.toml multisupport_acceptance_inventory_uses_narrow_dec_046_policy
Hand calculation:
validation/hand_calcs/nonlinear/assembled_multi_support_rotational_acceptance.md.
Test record, with the recorded run of 2026-07-10:
nl-assembled-multi-dof-rotational-accepted-original.md.