Finite element analysis (FEA) output is interpreted by examining a simulated product's response to specified loads and constraints, then comparing results with material limits and design criteria. A coloured plot alone does not prove safety: check its scale, units, assumptions and mesh quality.
FEA divides a digital model into small elements called a mesh. Software applies defined loads, material properties and boundary conditions, then estimates each element's response.
| Output | How to interpret it |
|---|---|
| Stress | Shows internal force per unit area, usually in Pa or MPa. Locate maximum stress and compare it with the material's yield strength or allowable stress. |
| Strain | Shows proportional deformation. Normal strain is . High localized strain may indicate permanent deformation. |
| Displacement | Shows how far and in which direction points move. Compare maximum displacement with the product's functional tolerance. |
| Factor of safety | Compares allowable strength with working stress: . A value below predicts failure. |
First, check the legend, units and deformation scale. Software often exaggerates displayed deformation, so a severe-looking image may represent small numerical displacement. Identify stress concentrations near holes, sharp corners, supports or load points.
Evaluate reliability by refining the mesh around complex geometry and high-stress regions. Mesh convergence occurs when further refinement produces little change. Unrealistic constraints, inaccurate material data or incorrect loads can invalidate precise-looking results.
A common misconception is that red means failure. Red only marks the plot's highest value; failure requires comparison with material properties and specifications.
Exam technique: For B2.2 modelling and prototyping, identify FEA as virtual modelling used to predict performance before physical prototyping. State the location and numerical maximum, compare it with a relevant criterion, then evaluate assumptions and limitations. This demonstrates interpretation rather than merely describing colours on the plot.