I have posted this info here before. You can find it by searching the Technet Archives using "accelerometer" and you should see it. I don't have the time to repeat all of the information right at the moment.
Strain gauges don't work very well for measuring stress/strain from inertial movement, but there are wireless accelerometer systems out there you can place on your board and monitor and store all movement, shock, vibration, etc.
They work in conjunction with a receiver/datalogger. It keeps track of everything over a long period of time.
I used them to find the vibration or random cycling that was causing MEMS gyrometers to fail.
It wasn't during fabrication of the MEMS itself.
It wasn't handling during transit, either from the fabricator to the manufacturing plant, nor from the plant to shipping, nor from the distribution center to the avionics assembly factory, nor from the vibration or shock of the plane itself.
If was from the cavitation during the inline cleaning process after reflow. 
When the inline cleaner wash and rinse pressure settings were adjusted down, but with a longer dwell time, not only did the problem disappear altogether, but the cleanliness contamination readings as measured by SIR, Ionograph, and ion chromatography testing went way down. Surprise!
We learned a huge amount of lessons from this. Simple things like routing a populated assembly out of a panel can destroy many sensitive components.
Odin

-----Original Message-----
From: TechNet <[log in to unmask]> On Behalf Of Rivera, Raye
Sent: Wednesday, August 25, 2021 2:22 PM
To: [log in to unmask]
Subject: [TN] Strain or strain rate spec for PCBAs

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Hello Technetizens,

Does anyone know of a spec or criteria for acceptable strain or strain rate for a PCBA?

We are using strain gauges to understand how much strain is placed on a PCBA inside one of our products during typical shipping processes.

I know that IPC-TM-650, 2.4.41.2A tells how to measure coefficient of thermal expansion by this method, but I can't find anything about mechanical force, or how much is too much.

Best regards,
Raye Rivera
Quality Manager