Even seasoned engineers facepalm over these FEA blunders. From unit mishaps to ‘phantom’ contacts, learn how to dodge career-worthy mistakes.
Fail # 1: The “Invisible” Units Catastrophe
Story: An aerospace team simulated a satellite bracket at 100 kN load, only to realize post-fabrication that the software had defaulted to Newtons (1 kN = 1,000 N). The bracket snapped during testing.
Lesson:
- Always declare units explicitly in input files, software GUI
- Use dimensionless numbers where possible (e.g., strain)
- Pro Tip: Create a units checklist template for your team
Fail # 2: The Mesh That Hid the Stress
Story: A pressure vessel analysis showed low stress everywhere—because the mesh was too coarse at fillets. The prototype cracked at the “smoothed-out” stress concentration.
Lesson:
- Never trust a mesh without local convergence studies
- Use mesh metrics (aspect ratio, skewness) and physics (stress gradient) to refine
- Pro Tip: ANSYS/Abaqus users: Leverage automated adaptive meshing for critical regions
Fail # 3: The “Magic” Fixed Support
Story: A bridge simulation assumed perfect fixity at piers. Real-world flexibility caused resonant vibrations that weren’t predicted.
Lesson:
- Real supports are never perfectly fixed or frictionless
- Model stiffness/damping explicitly (e.g., with spring elements or empirical data)
- Pro Tip: Test boundary condition sensitivity by varying stiffness ±20%
Fail # 4: The Contact That Wasn’t There
Story: A bolted joint analysis ignored friction, assuming “bonded” contacts. The assembly loosened under vibration, just as physics predicted (but the simulation didn’t).
Lesson:
- Default “bonded” contacts are often unrealistic
- Always question: Could slip/separation occur?
- Pro Tip: Use frictional contact + pretension for bolts, and check status (.STAT files in ANSYS)
Fail # 5: The Material Model Mirage
Story: A nonlinear analysis used bilinear plasticity for a polymer—ignoring rate-dependence. The real part deformed 3× faster than predicted.
Lesson:
- Plasticity ≠ Hyperelasticity ≠ Viscoelasticity
- Match material models to test conditions (strain rate, temperature)
- Pro Tip: Run a 1-element test simulation to verify your material curve input
How to Avoid These Fails:
- The “Pre-Mortem” Checklist: Before hitting Solve, ask: What could go wrong?
- Peer Review: Have a colleague spot-check assumptions
- Physical Sanity Check: Compare FEA results to hand calcs/analogies
The best FEA engineers aren’t those who never fail—they’re the ones whose mistakes teach the whole industry.