Remotely operated strain gages

[mighoser]

I'm a mechanical so be gentle. Is there a compact battery powered strain gage which samples 10,000 S/sec, survive 100G min (500G pref.)and is able to store date for download later? Looking for four channels but would settle for two 2-channel modules. I only need 5-10 seconds of data. Must fit inside one or two demil. 20mm round(s) (case and projectile). The inner case portion is a cylinder approximately 25mm diameter x 65mm long. The projectile could be bored for wire access. Actual strain gages would be place outside of the round in close proximatey. I've talked with invocon and microstrain and they don't have any out of the box solutions. KMT-GMBH has a product which could fit but I would need to come up with a data storage device. Any thoughts?

 

[itsmoked]

I cannot imagine anything off-the-shelf for this.

Gads.. One of the first things to make this hard is 10K samples per second for how long? This kind of data piles up very quickly needing lots of memory.

Can you use a trigger, so no data is collected until "x"G is reached?

Also most systems will require a timebase, which is usually crystal based. Crystals don't do 100G. So something like an RC would be needed. You would desire close temperature calibration to provide the correct time/acceleration numbers.

Never mind the acceleration do you have a method to soften the deceleration?

If this projectile is fired in the conventional manner do you have any numbers on how hot the inside will get after being swedged down a rifled barrel by a kjoule chemical reaction against the back end?

How will access be achieved? If the rear is threaded how can you prevent 100kpsi gas from leaking in?

The round would only reside in the barrel about 1 millisecond so at 10kSPS you would only get about 10 samples... Seems like you would want more than that.

Certainly sounds like a heck of a challenge.. Fun too!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[mighoser]

Keith,

We aren't going to be firing the rounds which this devise would sit in. Picture a conveyor belt made of linked ammunition inside a mostly sealed box (no access for wires). The opening of the box goes up to a gatling gun where the ammo to exchanged for fired cases. I'm interested in measuring the links while this is going on. No heat issues. I've measured with normal wired strain gages but they only can collect a little data before they snap off. I'm just looking for something to collect the data then download.

Thanks,

 

[itsmoked]

Hi mighoser. (mig hoser LOL)

Ahhh.. that explains how you can put something on the outside.

Well your requirements have dropped substantially in my opinion. Multi hundred G stuff is still a bit of an issue, as is the form factor.

I will look around.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[DaveScott]

I'm not sure you could get something off the shelf, but I could offer the following idea:
I assume you want the strain gauges not to work in a bridge fashion (each strain gauge is checking one side of the link)?
If you need two, then consider a crude mini MP3 recorder (they are really small, now), but with a suitable signal amplifier in between. They are stereo & sample at about 48,000 per sec. Of course, MP3 does fiddle around with the signal, but maybe it could work, who knows?