// Workflow for fatigue and durability analysis - cycle counting, damage accumulation, and fatigue life prediction.
| name | abaqus-fatigue-analysis |
| description | Workflow for fatigue and durability analysis - cycle counting, damage accumulation, and fatigue life prediction. |
| allowed-tools | ["Read","Write","Edit","Glob","Grep","Bash(abaqus:*)","Skill"] |
Predict fatigue life from FEA stress results using S-N curves and damage accumulation.
Route here when user mentions:
Route elsewhere:
/abaqus-static-analysis/abaqus-static-analysisAbaqus has limited native fatigue capabilities. The typical workflow is:
For full fatigue analysis, consider external tools: fe-safe, nCode, FEMFAT.
Before fatigue analysis:
Use /abaqus-static-analysis for constant loads or /abaqus-dynamic-analysis for time-varying.
Ensure output requests include:
S - Stress components (principal, Mises)E - Strain componentsPEEQ - Equivalent plastic strain (for low-cycle)Find the maximum stress location:
/abaqus-odb to extract peak stressFor constant amplitude: single max/min stress values. For variable amplitude: full stress-time history for rainflow counting.
Use appropriate method based on loading and life regime.
Apply Basquin equation for life, Miner's rule for cumulative damage.
| Approach | When to Use | Data Needed |
|---|---|---|
| Stress-life (S-N) | High-cycle (N > 10^4) | S-N curve |
| Strain-life (e-N) | Low-cycle (N < 10^4) | Coffin-Manson params |
| Fracture mechanics | Crack growth | da/dN curve |
| Loading | Analysis Method |
|---|---|
| Constant amplitude | Single static analysis |
| Variable amplitude | Multiple loads + rainflow |
| Proportional | Single load case |
| Non-proportional | Critical plane method |
| Method | Use Case |
|---|---|
| Goodman | Conservative, tensile mean |
| Gerber | Less conservative |
| Soderberg | Very conservative |
| SWT | Strain-life with mean stress |
If unclear, ask:
| Parameter | Typical Values | Notes |
|---|---|---|
| S-N slope (b) | 0.08-0.15 | Lower = longer life |
| Endurance limit | 40-50% UTS (steel) | Stress below which infinite life |
| Fatigue notch factor (Kf) | 1.0-3.0 | Kf = 1 + q(Kt-1) |
| Notch sensitivity (q) | 0.7-0.95 | Higher for stronger steels |
| Problem | Cause | Solution |
|---|---|---|
| Unrealistically short life | Stress singularity | Use Kf correction, refine mesh away from singularity |
| Wrong units | MPa vs Pa mismatch | Verify stress units match S-N data |
| Unconservative prediction | Missing mean stress | Apply Goodman/Gerber correction |
| Very long calculated life | Stress below endurance limit | Check if stress > endurance limit |
/abaqus-static-analysis - Base stress analysis/abaqus-dynamic-analysis - Time-varying loading/abaqus-amplitude - Cyclic loading definition/abaqus-odb - Extract stress history from resultsFor API syntax, equations, and code examples, see:
Analyze multi-body contact. Use when user mentions parts touching, friction between surfaces, bolt-plate contact, press fit, or assembly with contact.
Complete workflow for coupled thermomechanical analysis. Use when user mentions thermal stress, thermal expansion, or temperature causing deformation.
Complete workflow for dynamic analysis. Use when user mentions impact, crash, drop test, transient, or time-varying response. Handles explicit and implicit dynamics.
Complete workflow for modal/frequency analysis - extract natural frequencies and mode shapes. Use for vibration analysis and resonance avoidance.
Complete workflow for static structural analysis. Use when analyzing stress, displacement, or reaction forces under constant loads. For strength and stiffness evaluation.
Complete workflow for heat transfer analysis - steady-state and transient thermal. Use when user asks about temperature distribution, conduction, convection, or heat flow.