BrConfig (Strain Configuration)
Used to determine which equation should be used for the strain calculation. A positive or negative code can be entered. A negative code reverses the output polarity.
Right-click the parameter to display a list.
| StrainCalc() BrConfig Code |
Configuration |
|---|---|
| 1 |
Quarter-bridge strain gage1:
CASE 1 - If a Campbell Scientific 4WFBXXX Terminal Input Module is utilized, the bridge set up is as depicted in Case 1. For this set up, a negative Option (-1) should be used for the datalogger to output positive strain values when the strain gage experiences positive strain. CASE 2 - If the excitation voltage polarity is reversed, or the output polarity is reversed, or if the bridge is configured as shown in Case 2, then a positive Code (1) should be used for the datalogger to output positive strain values when the strain gage experiences positive strain. |
| 2 |
Half-bridge strain gage1. One gage parallel to strain, the other at 90° to strain:
|
| 3 |
Half-bridge strain gage. One gage parallel to +ɛ, the other parallel to -ɛ1:
If a Campbell Scientific 4WFBXXX Terminal Input Module is utilized with the G2 gage wired to positive excitation and the G1 gage wired to ground, then the bridge set-up is as depicted above. For this set up, a negative Option (-2) should be used for the datalogger to output positive strain values when the G1 strain gage experiences positive strain. If the excitation voltage polarity is reversed, or the output polarity is reversed, or if the output data needs to be positive when the G2 strain gage sees positive strain, then a positive 2 should be inserted into the Code parameter. |
| 4 |
Full-bridge strain gage. Two gages parallel to +ɛ, the other two parallel to -ɛ1:
|
| 5 |
Full-bridge strain gage. Half the bridge has two gages parallel to +ɛ and -ɛ, and the other half to +nɛ and -nɛ 1:
|
| 6 |
Full-bridge strain gage. Half the bridge has two gages parallel to +ɛ and -nɛ , and the other half to -nɛ and +ɛ1:
This example assumes that the bridge (shown above) is set up such that the strain is considered to be positive when the G1 and G4 strain gauges experience positive strain (tension) while the G2 and G3 strain gauges experience negative strain (compression). In other words, when G1 and G4 increase in resistance (while G2 and G3 decrease in resistance), the strain is considered to be positive. The default setting for the output was configured for this bridge setup, and the datalogger's output strain data will be positive when the G1 and G4 strain gauges experiences positive strain. If the excitation voltage polarity is reversed, the output polarity is reversed, or if the output data needs to be positive when the G2 and G3 strain gauges experience positive strain, then Reverse should be clicked on. |
1Where
- n : Poisson's Ratio (0 if not applicable).
- GF: Gage Factor.
- Vr: 0.001 (Source-Zero) if BRConfig code is positive (+).
- Vr: –0.001 (Source-Zero) if BRConfig code is negative (–).
and where:
- "source": the result of the full-bridge measurement (X = 1000 • V1 / Vx) when multiplier = 1 and offset = 0.
- "zero": gage offset to establish an arbitrary zero.
Type: Constant