EV battery pack DFMEA
A design FMEA for an electric-vehicle battery pack. The engine flattens the failure chain, computes RPN = S × O × D, and derives the AIAG-VDA Action Priority — keeping a S10 safety failure High even when its RPN looks low.
For the design / reliability engineer
What this shows
A design FMEA (DFMEA) on the highest-stakes subsystem in an electric vehicle. The nested chain reads item → mode → effect/cause/controls: a cell module that can suffer thermal runaway or capacity fade, and a busbar joint that can go high-resistance. Each effect carries a Severity, each cause an Occurrence, each control the Detection it earns — the three AIAG-VDA 1–10 scales.
The engine computes the priority rather than just tabling it. It flattens to one worksheet row per (item, mode, cause), multiplies RPN = S × O × D, and — the part that matters — derives the AIAG-VDA Action Priority, which is severity-primary. The thermal-runaway row sits at S10·O3·D4 with an RPN of 120; a naive RPN sort would rank it below a noisier low-severity defect, but Action Priority keeps every safety failure (S = 9–10) at High regardless. The flag: ap >= High directive highlights exactly those rows so the safety-critical work rises to the top.