An Improved Strain Gage Signal Conditioner for Dynamic Stress Measurement
Abstract
Recent developments in turbojet engine testing have led to the reevaluation of the signal conditioning circuit used with single-active-arm strain gages for dynamic stress measurement. As may be expected, there is an increased demand for accuracy and for extended data bandwidth. Achievement of these requirements is made more difficult by the proliferation of fast rise time digital electronic circuitry with its accompanying generation of electrical noise. Also complicating the picture is the practice of engine manufacturers using small-diameter, high-resistance thermocouple wire as lead wire for the strain gages. The resistance of this wire changes significantly with temperature and also is unbalanced between the two leads. A new signal-conditioning circuit has been developed under AEDC Air Force Project No. DC97EW that accommodates changing lead wire resistance without loss of accuracy and still maintains low noise and good common-mode rejection of unwanted electrical noise. This signal conditioner also includes a novel DeltaR calibration circuit that provides a more accurate simulation of actual gage-resistance change.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1990
- Accession Number
- ADA541403
Entities
People
- B. G. Mahrenholz