An experiment to get the accuracy of strain gages

Now all subsequent readings would subtract the averaged initial offset from the reading providing a neutral, balanced output. As for the speed and frequency, it will depend on how fast the pressure could change. That is Is it flexible enough to distort sufficiently to measure with a strain gauge?

We measure the change of voltage with respect to the excitation voltage. The example shown in figure 5 is simple. P Start recording to disk, wait a few seconds, then pop the soda can lid, wait a few seconds, and turn off recording.

I have yet to try to glue a strain gauge to it.

However, it does not permit the continuous monitoring of the excitation voltage. At this stage, our bridge is balanced and from lecture we know that and we know that. You might be able to use a laser vibrometer LDV to measure the change in shape of the pipe directly to an accuracy of nm, or even pm with special image processing software.

A possible sequence might be: Yes unfortunately it has to be quite small. Essentially, the user starts the VI and pushes a toggle to start an initial bridge balance. G when "Balanced Completed" turns on, turn off the bridge balance option.

They can measure steady-state as well as dynamic effects. One can add shunt resistors to simulate known strains and compare the measured-strain x-axis to the known-strain via shunt resistor y-axis.

Strain Gauges Experiment - Lab Report Example

After an average offset is established, turn off the initialization process. Insert at least two different shunt resistors and perform a linearization on these results to create a slope and intercept for the calibrated-strain final output.

This type of loop required that all tasks within Stack Zero be performed then those tasks in Stack One, etc. First, thank you for your genuine interest in this! National Instruments discusses strain gage configurations and balancing. Your virtual instrument needs a mechanism to zero out or balance the bridge.

Either degrees or degrees, depending if we go with room temperature or that of the human body. Use the LabView help to get more information on shift registers. Create them by right clicking on the while loop perimeter and "add a shift register". In this mode, there is not a conflict for cpu resources.

The voltage across nodes C-A should be zero initially, i. On the left and right sides of the while loop there are down and up arrowheads.

How to know a strain gauge's accuracy?

M Repeat if another shunt resistor is also being used. Q Switch soda cans if you have a partnerrebalance the bridge, and perform step E through P again. Figure 7 shows one possible mode to balance the bridge.

One idea I had was to put the gauge inside the tube, to be affected by the flow, but that would probably cause short circuit problems. That will produce a very small strain unless you have a flexible pipe, but a flexible pipe could give calibration problems by not staying circular i.

Connecting a Quarter-Bridge strain gage to channel 0. Hmm, the tube I have in mind is plastic of sorts. I found that a constantan alloy, and consists of two identical grids, with one stacked directly above and insulated from, the other.

But the 4 resistors will not be perfectly balanced.Figure 4: Wheatstone bridge configuration with R4 acting as strain gage.

Determine how you will connect the 3 strain gages on the plate and the soda can to build the circuit of figure 4. coatings, and electrical resistance strain gages.

In this experiment the strain gage will be utilized. There are three steps in obtaining experimental strain measurements using a strain gage: 1.

Selecting a strain gage 2. Mounting the gage on the test structure and 3. Measuring strains corresponding to specific loads. The purpose of this experiment is to improve the results obtained in experiment 1 by the previous measurement method by using a Wheatstone bridge (Figure 2) that comprises of four nominally identical strain gauges.

ME – Experiment 5: Stress Analysis by Using Strain Gages Theory Page 3 / 15 3- Gage size should be as small as possible to adequately estimate the strain. STRAIN GAGES practical Strain GaGe meaSurementS introduction W ith today’s emphasis on product liability and energy stress-strain diagrams.

To do accurate stress analysis studies for these materials, it is necessary to determine the stress-strain properties, including Poisson’s. measure the strain requires accurate measurement of very small changes in resistance.

For example, suppose a test specimen undergoes a substantial strain of µε. A strain gauge with a gauge factor GF = 2 will exhibit a change in electrical resistance of only 2•( × 10–6) = %. For a Ω gauge, this is a change of only Ω.

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An experiment to get the accuracy of strain gages
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