ES180 : Technological Science 1
Strain Gauge
Laboratory Report

By Akash Sherchan
Student I.D. #: 1124433
University of Warwick

Summary
The strain gauge laboratory session had a lot of aims and one of the main aims was to provide us with experience in using circuits based on operational amplifiers and examine the characteristics of these circuits when they amplify DC signals. Another aim was to also investigate the use and characteristics of resistive strain gauges. The overall objective was to understand the how these widely used transducers are used and how they behave. This will be done through custom pre-built electronic circuits which will then be used to amplify signals from a resistive strain gauge when weighed down with …show more content…

Another graph was plotted for this.

3) Strain gauge bridge
In this exercise we examined the use of strain gauges with an operational amplifier. The ‘Analogue Experimental Transducer’ (figure 6) was used for this experiment. Strain gauges were bonded to the top and bottom of the beam to measure its deflection. Also, it is used to gain a measure of the load applied to the end of the beam.

Figure 6: The ‘Analogue Experimental Transducer’. Equipment and layout for third section (strain gauge)
Figure 6: The ‘Analogue Experimental Transducer’. Equipment and layout for third section (strain gauge)

Figure 6
Figure 6

Figure 5
Figure 5
Stretching a strain gauge increases its resistance while compressing it makes the resistance fall. Therefore, a load applied to the end of the beam will cause it to deflect downwards, increasing the resistance of the strain gauge on top of the cantilever while at the same time decreasing the resistance of the gauge on the bottom part of it.
The circuit for the differential omp-amp had already been set up for us and the configuration is given below in figure 7.
For a differential op-amp the following equation applies:
VO = (V1 – V2) x R6/R5
Figure 7
Figure 7

3.1 As stated earlier the circuit was already constructed with the values of R5= 12 kΩ and R6= 1.2MΩ. With this we could calculate and expect Vo (output voltage) to be 1V. (V1 = 1.01V AND V2 = 1.00V).

We then had to wire the analogue experimental transducer to