Wheatstone Bridge Circuits for Force and Moment Measurement — Lesson 2

This lesson covers the application of Wheatstone bridge circuits in force and moment measurements. It delves into the concepts of summing and differencing circuits, explaining how they are used in the measurement of different physical quantities. The lesson also discusses the role of resistances in these circuits and how changes in these resistances affect the output voltage. It further explains the concept of fully active Wheatstone bridge and its advantages. The lesson provides a detailed explanation of how these circuits are used in a wind tunnel model to measure forces and moments. It also explains the concept of strain gauges and how they are used in these circuits. The lesson concludes with a discussion on the positioning of strain gauges for effective force and moment measurement.

Video Highlights

01:16 - Explanation of the current flow in a summing circuit and the calculation of voltages at different points.
05:34 - Detailed explanation of a fully active with stone bridge and its application in a wind tunnel test.
09:44 - Detailed explanation of the internal sting balance and its application in a wind tunnel test.
14:48 - Explanation of the measurement of lift using a differencing circuit.
25:29 - Discussion on the measurement of pitching moment using a summing circuit.

Key Takeaways

- Wheatstone bridge circuits are used in force and moment measurements.
- Summing and differencing circuits play a crucial role in these measurements.
- Changes in resistances in these circuits affect the output voltage.
- Fully active Wheatstone bridge offers advantages like temperature compensation and linear relationship between output voltage and resistance change.
- Strain gauges, bonded to the wind tunnel model, change their resistance based on the strain they experience, influencing the output voltage.
- The positioning of strain gauges is crucial for effective force and moment measurement.