Case Studies
Hopkinson Bar Testing - Testing Materials for Reactions to Stress Pulses
THE PROBLEM
This customer is involved in testing materials for how they react to stress pulses. The idea is to introduce a stress pulse into the Material Under Test (MUT) and monitor it as it travels through the material. This method of material characterization is also known as "Hopkinson Bar" testing.
Multiple sensors pick up the reaction of the material and provide outputs which need to be digitized. These outputs are transient signals of approximately 2 Volts and have a rise time of approximately 600 nanoseconds.
The resulting system must be programmable under LabVIEW for Windows NT, as the customer already has the analysis program written in that environment.
GAGE'S SOLUTION
A four-board CompuScope 8012A/PCI system, housed in a GagePC/PCI 586, will provide an ideal method of capturing the eight signals simultaneously. These signals can be displayed on the PC screen using GageScope software.
GageScope also allows the customer to specify a "Trigger Delay" in order to view different parts of the signal(s).
CompuScope 8012A/PCI is a PCI bus based A/D card which acts as a Transient Digitizer in this application. The card takes a "snapshot" of the input signals: once data is captured, software can access every part of the record. For example, if data before the trigger is of interest, software can read just that portion; if the focus is on data hundreds of microseconds after the trigger, software can read that portion, and so on.
The length of the record the customer can capture will depend upon the on-board memory of the CompuScope 8012A card. The standard memory is 512 Ksamples, i.e. 256 Ksamples per channel. Models are also available with 1 Meg (512K per channel), 2 Meg (1 Meg per channel) or 4 Meg (2 Meg per channel) memory. If the customer were to select the ISA version of the cards, the on-board memory could go as high as 16 Meg (8 Meg per channel).
The CompuScope cards will be housed in a GagePC/PCI 586 - an industrial grade, 19" rackmountable computer. This computer will consist of an "Active" backplane which has nine PCI and four ISA slots. All four ISA slots and four of the PCI slots will be used up by the CompuScope cards. Additional PCI slots will be available for a video card and SCSI cards.
LabVIEW for Windows NT drivers will be provided, so the customer's software can read data from the CompuScope card instead of the stand-alone oscilloscope.
Needless to say, the reading from the CompuScope cards will be at least 100 times faster than the stand-alone scope. This is due to the fact that PCI bus is at least 100 times faster than GPIB.
PRODUCT RECOMMENDED
Multi-Card (4) CompuScope 8012/PCI system, Master/Slave
GagePC/PCI 586, industrial grade 19" rackmountable computer
GageScope Multi-Card software
CompuScope Driver for LabVIEW for Windows NT
This application note is provided "as is" without any warranties of any kind, either expressed or implied, including but not limited to the implied warranties of merchantability or fitness for a particular purpose. Gage Applied Technologies further does not warrant the accuracy and completeness of the material contained herein. Gage Applied Technologies may make changes to this material, or to the products described in it, at any time without notice.
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