Impact Test-Correlation Example
A worked example comparing an FEA impact prediction with a physical test result and assessing the correlation.
Problem
An impact test on a 6 mm aluminium plate gave: dent depth 8.2 mm, no perforation. The FEA predicted: dent depth 9.1 mm, no perforation. The test uncertainty is estimated at +/- 0.5 mm. Assess the correlation.
Solution
Predicted dent: 9.1 mm Measured dent: 8.2 mm Difference: 9.1 - 8.2 = 0.9 mm Test uncertainty: +/- 0.5 mm The difference (0.9 mm) exceeds the test uncertainty (0.5 mm). The prediction overestimates the dent by about 11%. However, the perforation status agrees (both predict no perforation), which is the primary engineering output.
Interpretation
The correlation is reasonable — the prediction overestimates the dent by 11%, which may be acceptable for a conservative assessment. The perforation status agrees, which is the primary engineering output. The overestimation may be due to the material model (slightly too soft), the friction coefficient (too low, allowing more sliding), or the mesh (slightly too coarse). The correlation should be documented with the quantitative comparison and the assessed uncertainty.