Strain gage ¼ bridge calibration with shunt signals

In the field of Experimental Stress Analysis hundreds and sometimes thousands of single strain gages are to be measured. Calibration of such big systems can be a tedious task.

Calibration of such big systems can be a tedious task. This paper explains how fast and precise calibration procedures can be carried out automatically by means of simple shunt resistor switching technique. It is a common technique to use shunt resistors to check strain gage measuring systems. But shunt signals are not considered to be very precise. Their main purpose today is to ensure that everything works properly.

This paper describes that with improved 3-wire and 4-wire technique shunt signals can serve as precise calibration signals. Also in situations where long connection cables with high wire resistances are used and where strain gages have large resistance deviations e.g. due to large pre-strain, the calibration error can be kept below 0.2%.

With the described method the whole system including the wiring of the strain gages can be calibrated without disconnecting the strain gage sensors and replacing them by a calibration standard. So the calibration procedure can be performed fully automatically and very fast.

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