vamseeachanta Common Errors and Fixes (+1)
Common Errors and Fixes
| Error | Cause | Fix |
|---|---|---|
Statics failed to converge |
Model not in equilibrium before modal | Fix statics first (see orcaflex-static-debug skill) |
Singular stiffness matrix |
Zero-tension lines or disconnected components | Check all lines have positive tension; verify all connections |
No modes found |
lastMode too low or model too simple | Increase lastMode; add more DOFs (finer segmentation) |
| Modal analysis hangs | Very large model with too many modes requested | Reduce lastMode or simplify model (coarser segments) |
| Unrealistic frequencies | Wrong units (mass, stiffness) or missing added mass | Verify line type properties; check hydrodynamic coefficients |
| Mode shapes all zero for an object | Object not included in modal analysis scope | Add object to ObjectName list in config |
| Duplicate frequencies | Symmetric model produces paired modes | Expected for symmetric configurations; modes are degenerate pairs |
Debugging Modal Issues
def diagnose_modal_failure(model):
"""Pre-check model before modal analysis."""
issues = []
# Check statics first
try:
model.CalculateStatics()
except OrcFxAPI.OrcaFlexError as e:
issues.append(f"Statics failed: {e} — fix statics before modal analysis")
*See sub-skills for full details.*