| Limitation | Mitigation | |------------|-------------| | Non-linear material behavior (plasticity) | Use superposition only in elastic regime; if plasticity occurs, apply Neuber correction or switch to incremental superposition. | | Crack closure effects | Account for residual compressive stresses reducing $K_I$ — beneficial crack-free condition. | | Stress gradient sensitivity | Use critical distance method (TCD) rather than point stress. | | Anisotropic residual fields | Perform eigenstrain reconstruction from multiple measurements. |
where $f$ is a fracture criterion (e.g., maximum principal stress, von Mises with hydrostatic cutoff, or a stress-intensity factor $K_I$ for a virtual crack nucleus). superposition benchmark crack free
| Step | Description | |------|-------------| | | Measure $\sigma_res$ via non-destructive techniques (X-ray diffraction, contour method, or incremental hole drilling). | | 2. Load Influence Matrix | Compute elastic influence coefficients for all critical load cases using FEA (e.g., unit loads at boundaries). | | 3. Superposition Solver | Combine $\sigma_res$ with scaled load cases to generate $\sigma_total$ maps. | | 4. Fracture Indicator | Evaluate a validated crack initiation criterion (e.g., $K_I$ at worst-case defect location). | | 5. Benchmark Pass/Fail | Pass if $K_I^max < K_I,th$ (threshold stress intensity factor) for all load combinations. | | | Anisotropic residual fields | Perform eigenstrain
Run Superposition at stock settings (no OC) on the preset. $K_I$ at worst-case defect location).