Has anyone measured strain with a USB DAQ device such as the 6008?

[DougFerguson]

I have a potential project were I would like to use my PDA/USB 6008 DAQ system to measure strain on a product in the field. I will not have access to AC voltage, so I must make use of batteries. I have done other DAQ applications with simple voltage inputs using this system, but of course strain gauges require excitation and signal conditioning. I don't need super accurate or fast reading (~100Hz) readings, so I am open to some crude solutions.

Any help you be appreciated.

Doug

[hoffiz]

Hi,

First I’m going to point you to some good strain gauges resources and then will see where we can go from there: the most important would be: Measuring Strain with Strain Gauges.

Now since your only source of excitation are the “Analog Output, 0-5volts” and the "DC output, 5 Volts  from the 6008, I would suggest making this experiment:  with no load applied, you should examine the zero point of the channel while excitation level is progressively raised using the analog output. Once instability in the zero reading is observed, you should lower the excitation until stability returns.

For signal conditioning you should be able to either build the bridge yourself or trying to measure the voltage drop directly from the strain gauge and check how accurate are the results.

Just as an inside note: our cDAQ-9219 for strain measurements is not an option since is not supported under DAQmx BASE.

[DougFerguson]

Thanks for the starting point. I was more concerned about the signal conditioning versus the excitation source, but I will experiment.

[saeed1812003]

zcsc