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20 Simulation

FEA & Stress Testing

Finite Element Analysis lets you stress-test a part on the computer before you ever cut metal or fire up the printer.

What is FEA?

Finite Element Analysis (FEA) splits your model into thousands of tiny pieces (elements) and calculates the stress on each one when you apply loads. It's a crystal ball for how your part will fail.

The Four Things You Must Set Up
  • Material: Pick the real material (aluminum 6061, PLA, steel). The yield strength is what decides if the part survives.
  • Fixtures: Which faces are bolted down or clamped. Wrong fixtures = wrong results, guaranteed.
  • Loads: Apply forces where they actually act in real life - not just on the middle of a face because it's convenient.
  • Mesh: Smaller elements give more accurate results but take longer to solve. Refine around corners.
⚙

Challenge

Find the minimum beam thickness that keeps the safety factor above 2.0 under a 500N load.

⚠ Predict First

Where do you think the highest stress will appear on a cantilever beam loaded at the tip?

FEA (Finite Element Analysis) divides a part into small elements and solves stress/strain equations for each.

Safety Factor = Material Yield Strength / Max Stress. Values > 1.0 mean the part survives. > 2.0 is typical for robotics.

Key inputs: material, loads, constraints (fixed faces), mesh size.

Red = high stress. Blue = low stress. Concentrate on the transition zones.

Guided Exploration
  1. Apply a 200N load. Note where peak stress appears and the safety factor.
  2. Double the force to 400N. Did the safety factor halve exactly? Why or why not?
  3. Find the minimum beam thickness that keeps safety factor above 2.0 at 500N.
1 Experience
2 Reflect
3 Theorize
4 Apply

Reading the Results

What the Colors Mean
  • Blue = low stress. This material isn't doing much work.
  • Green / Yellow = medium stress, safely within yield.
  • Red = near or over yield. The part is close to breaking.
Key Numbers
  • Max Von Mises Stress: The single highest stress in the part. Must stay below material yield.
  • Safety Factor: Yield / Max Stress. Aim for ≥ 1.5 for static loads, 3-4 for impact or fatigue.
  • Max Displacement: How far the part bent. Even 0.5 mm flex matters on a robot arm tip.
Warning: Bright red spots at sharp internal corners are often mesh artifacts, not real failure. Add a small fillet and re-run - if the red disappears, it was the mesh, not the part.

Full Robot Assembly - the kind of system you'd run FEA on to find weak points before building.

Stage 2 Pause and Reflect
✓ Your reflections are saved automatically
Stage 4 Apply What You Learned

Run an FEA study on a robot arm bracket that must hold a 5kg payload.

  • Define the load: gravity pulling 5kg at the end of the arm
  • Set fixtures: which bolt holes attach to the chassis?
  • Apply the correct material (start with aluminum 6061)
  • Run the study and find the max stress and safety factor
  • If safety factor is below 1.5, identify what to thicken
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