Failure forensics: computed tests

Computed. Two reliability scalings that decide most forensic arguments, and the one that decides whether a trend is real.

1. Accelerated ageing is steep

Temperature excess	Rate factor
10 K	2.0×
20 K	4.0×
30 K	8.0×
50 K	32.0×

A 30 K overshoot ages 8× faster. Practical: a warranty claim based on run-hours at nameplate temperature is wrong by an order of magnitude if the unit ran hot.

2. Weibull shape identifies the failure mode from the data alone

Shape β	Hazard slope	Reading
0.7	falling	infant mortality — a manufacturing defect
1.0	flat	random — no wear-out signature
1.5	rising	early wear-out
3.0	steep	classic wear-out

Practical: fitting β separates "bad batch" from "end of life" without opening the unit — the single most useful forensic number.

3. What this does not do

It does not identify a mechanism. It narrows the class. A β of 3 is consistent with wear of several kinds; only a strip-down or an oil analysis separates them.

Incoprea Research · 3 November 2026. Composition and computation. No experiment performed.