load cell interface for impact testing


Thread Starter


I would like to measure the impact load during the collision. I now have a Kistler quartz load cell but am not sure of interface sequence in order to channel the impacted signal to a data acquisition software (LABVIEW)

I believe such measurements need a specific Analog to Digital convertor card to channel signals because of the short durations of interesting impact events (fractions of one microsecond to a very few microseconds).

Any suggestions?
You need a card that samples at least twice as fast as the signal of interest (Nyquist theorum). In practice I would recomend 10 times faster. For example 100Hz signal you would want a 1kHz Samples/sec Data Acquisition card.

Curt Wuollet

A good place to start would be the stuff intended for DSOs (Dig. storage scopes) And even there you would require fairly good one shot performance depending on how long your events are (depth) and how fast you need to sample for waveform fidelity. If you are using piezo force sensors, chances are the important part of the event will be quite brief, especially in a low mass collision. A good start might be to rent a fast and deep DSO for a month. This would let you definitely capture the event and determine what your real world needs are with little trial and error. It may be that you need a mostly hardware front end writing to a buffer you can copy at a more leasurely pace. The common data acquisition cards aren't in this league. Once upon a time we solved this by using a scope that could do the job and offloading the data for processing elsewhere. This may still be an attractive method. I can't mention what we were doing, but suffice it to say it would be much easier now. A google search shows many boards that purport to capture at these speeds. I would compare their dataset to that captured by a "real" DSO (tektronix, gould, etc.) as sampling is easy, but accurate sampling at speed is anything but. High speed waveform capture will change your whole perspective on measurement.