What are the factors affecting accuracy of strain gauges?
The factors affecting strain gage design and construction include of foil alloy, backing, pattern, and temperature characteristics. Over 250,000 unique strain gage constructions are possible, each particularly suited to a specific set of application conditions.
What are the typical source of errors for strain gauge measurement?
Bridge non-linearity and uncertain ability of gauge factor are the 2 most important sources of error of strain gauge. The gauge factor has been determined based on information presented by the supplier. The linearity of strain gauge configuration can be determined based on the results of calibration.
How do you increase the sensitivity of a strain gauge?
For the same strain gage, changing the bridge configuration can improve its sensitivity to strain. For example, the full-bridge type I configuration is four times more sensitive than the quarter-bridge type I configuration. However, full-bridge type I requires three more strain gages than quarter-bridge type I.
How does temperature affect the operating characteristics of a strain gauge?
With all strain gages in a bridge at the same temperature and mounted on the same material, any changes in temperature affect all gages in the same way. Because the temperature changes are identical in the gages, the ratio of their resistance does not change, and the output voltage of the gage does not change.
What are the factors affecting the selection of gauge?
The following factors govern the choice of a different(particular) gauges:
- Cost of construction and funds available for the railway project.
- Volume and nature of traffic.
- The intensity of population.
- Industrial and commercial development of the locality.
- Prospects of future development of the area.
What factors can affect the sensitivity of resistance strain gauge?
Sensitivity (S) where is affected by the change in wire length, cross-section area, and the piezo-resistance effect of the wire material. Since most metal materials have the Poisson’s ratio around 0.25 to 0.35, the 1 + 2 n term in the strain sensitivity factor S is expected to be 1.5 to 1.7.
Which factors can cause error in the measurement output of strain sensor?
Error sources in resistance strain gauges measuring system are numerous; for example, error due to the transverse sensitivity of the strain gauges, error due to temperature, error due to misalignment, and error due to the Wheatstone bridge’s nonlinearity.
How is a strain gauge noisy late and wrong?
Another often-overlooked source of noise is leakage to ground through the strain gage and/or the cabling. If excessive, this leakage can cause noise transfer from the specimen to the gage circuit, since even supposedly well-grounded specimens may carry some noise.
What is the sensitivity of the gauge?
The strain sensitivity k of a strain gauge is the proportionality factor between the relative change in resistance ΔR/R0 and the strain ε to be measured: ΔR/R0 =k⋅ε. The strain sensitivity yields a dimensionless number and is designated as the gauge factor.
How does temperature affect strain measurement?
The materials of the strain gauge itself have a non-zero coefficient of thermal expansion. Changes in temperature will cause the strain gauge itself to expand or contract, independent of any strain inthe part to which it is attached.
How does strain gauge measure temperature?
A technique was developed to measure the thermal expansion of solids in the temperature range from -50 to 175 C. The technique uses strain gages to measure expansion and Type J (iron/constantan) thermocouples to measure temperature.
What is factor affecting selection of gauge in railway?
Following are the factors affecting the choice of a gauge: Traffic Condition: If the intensity of traffic on the track is likely to be more, a gauge wider than the standard gauge is suitable.
What is a strain gauge and how does it work?
A Strain gage (sometimes referred to as a Strain Gauge) is a sensor whose resistance varies with applied force; It converts force, pressure, tension, weight, etc., into a change in electrical resistance which can then be measured.
What are the factors that affect the strain reading?
The case arises when the temperature changes, and the specimen is subjected to a different temperature during performing the test. In this case, the strain reading will be affected by several factors that cause error in the reading.
What happens if the strain gauge is not distributed homogeneously?
It should be noted that if the strain is not distributed homogeneously, the average of the strain under the measuring grid is converted into the relative change in resistance. As a result of this, if the wrong active length of the strain gauge is chosen, the values measured for strain and material stress will be too small or too large.
How does temperature affect the Gage reading?
When the temperature changes, the specimen will expand, and this expansion causes and increases or decreases in strain reading. The temperature change also affects the gage itself, and the gage can’t read correctly. This strain change in the specimen and the gage is called thermal output.
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