Nonlinear solver — Singular Tangent Diagnostic
Nonlinear solverPASS · 0%Nonlinear iteration, tangent, path-following, and state-management verification. Checks: limit-point singularity and underconstraint distinction.
- Tolerance:
- 5%
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Open & Solve in BrowserProblem statement
- Geometry
- Approach the snap-truss limit point and separately solve an underconstrained rigid-body model.
- Material
- Constitutive or analytical definition: Both systems can have singular tangents, but only one lies on a valid nonlinear equilibrium path.
- Boundary conditions
- Required solver capability: nonlinear_linear_solver_integration. Use the loading/path control stated in the setup and preserve the complete response history.
- Measured quantity
- Report near-singular tangent/path-following transition for the valid snap-through model; report structural singularity/nullspace for the invalid model; never return a false converged state.
WebCAE Terminal
Paste these commands into the Terminal panel inside WebCAE. They use the same text DSL as the application; run one command per line:
units mm
frame up=z
material E=500000 nu=0.3
frame node at=0,0,0
frame node at=2500,0,25
frame member 1 2 section=rect w=10 h=10
frame support node=1 dofs="all"
frame load node=2 force=0,0,-15
frame solve static nlgeom=on method=arc steps=40 diagnostic=singularityResults comparison
| Reference value | valid=converged, underconstrained=failure (no false convergence) |
| Our result | valid=true, underconstrained=false |
| Deviation | 0% |
| Tolerance | 5% |
| Status | PASS · 0% |
| Element family | Beam element |
| Mesh details | ферма Мизеса (предельная сингулярность) vs незакреплённый механизм; webcae_solve |
Updated: 2026-10-19 · WebCAE solver