Test to failure first

Most test plans confirm that something works. A failure test asks a different question: how much can this take before it stops?

Why it matters

Knowing the limit turns a guess into a margin. If a bracket fails at four times its working load, you can stop worrying about it. If it fails at one and a half, you have found the week's real work.

How we run it

Instrument the part, raise the load in steps, and write down what happens at each one. Keep the broken part. It is the most honest drawing you will get.