Define analysis steps and procedures. Use when user mentions static analysis, dynamic step, frequency analysis, heat transfer step, or asks about analysis type, time increments, or nlgeom.
This skill defines analysis steps and procedures in Abaqus. Steps control what physics are solved and how the solution proceeds.
Route here when user mentions:
Route elsewhere:
/abaqus-bc/abaqus-load/abaqus-optimization/abaqus-outputAsk if unclear:
| Analysis Goal | Step Type | Key Parameter |
|---|---|---|
| Stress under constant load | StaticStep | nlgeom=OFF/ON |
| Natural frequencies | FrequencyStep | numEigen |
| Buckling modes | BuckleStep | numEigen |
| Transient dynamics (smooth) | ImplicitDynamicsStep | timePeriod |
| Impact/crash | ExplicitDynamicsStep | timePeriod |
| Heat conduction | HeatTransferStep | response |
| Thermal + structural | CoupledTempDisplacementStep | timePeriod |
| Harmonic response | SteadyStateDynamicsStep | frequencyRange |
Most common: StaticStep with nlgeom=OFF for linear stress analysis.
| Condition | nlgeom Setting | When |
|---|---|---|
| Small deformation, linear material | OFF | Default, fastest |
| Large rotation/displacement | ON | Thin structures, cables |
| Plasticity | ON | Material yields |
| Contact | ON | Parts touching |
| Buckling | ON | Post-buckling behavior |
| Convergence Difficulty | initialInc | minInc | maxInc |
|---|---|---|---|
| Easy (linear) | 1.0 | 1e-6 | 1.0 |
| Moderate | 0.1 | 1e-8 | 0.2 |
| Difficult (contact, plasticity) | 0.01 | 1e-12 | 0.05 |
For sequential loading:
previous='Initial'| Parameter | Purpose | Typical Value |
|---|---|---|
| timePeriod | Duration of step | 1.0 for static |
| initialInc | Starting increment size | 0.1 for nonlinear |
| maxNumInc | Maximum iterations | 100 |
| minInc | Smallest allowed increment | 1e-8 |
| maxInc | Largest allowed increment | 0.1-1.0 |
| numEigen | Modes to extract | 10 |
| deltmx | Max temp change per increment | 5.0-10.0 |
| Problem | Likely Cause | Solution |
|---|---|---|
| "Too many increments" | Convergence difficulty | Reduce maxInc, increase maxNumInc |
| "Negative eigenvalues" | Unconstrained or unstable | Check BCs, add stabilization |
| "Time increment too small" | Severe nonlinearity | Add stabilization, check material |
| "Explicit time increment" | Very small elements | Use mass scaling or coarsen mesh |
After step creation, verify:
For actual API syntax and code examples, see: