Is there a way to measure the structural strength of a connection?

I'm designing a very large spacecraft, and I'd like to attach an arm to the spacecraft.

Is there a way to measure just how strong the attachment is?

In engineering terms, this arm is a cantilever beam, and I'd like to know how much load it can take on the end before it breaks off.

To attach this arm to the spacecraft:

• only stock parts may be used (no mods), and
• the arm can be added to the spacecraft in the assembly building.