STRAIN GAGES Fundamentals: Piezoresistive Effect
Updated by: Olivia
On: 08 Jun, 2017
Viewed:590 times - 1 day, 13 hour, 54 minute, 41 second ago
Downloaded: 0 times -
Strain gages are based on the variation of resistance of a conductor or se...
Strain gages are based on the variation of resistance of a conductor or semiconductor when subjected to a mechanical stress.
For a wire having length 1, cross section A, and resistivity p. the electric resistance is
R = p
When it is stressed longitudinally, each of the three quantities that affect r R change and therefore R undergoes a change given by
= + -
The change in length that results when a force F is applied to a wire, within the elastic limit (Figure 2.4), is given by Hooke’s law,
= = Ee = E
where E is a constant for each material, called Young’s modulus, o is the mechanical stress, and r is the strain (unit deformation). r has no dimens ions, but to improve clarity, it is usually given in “microstrains” (1 micro- strain — 1 r — 106 rn/rn).
Consider a wire that in addition to a length I has a transverse dimension t. As a result of longitudinal stress not only does 1 change but t does too. The relationship between both changes is given by Poisson’s law
v = -
where v is the Poisson ratio. It usually ranges from 0 to 0.5; it is, for example, 0.17 for cast iron, 0.303 for steel, and 0.33 for aluminum and copper. Note that for the volume to remain constant, it should be v = 0.5.
As the fastest growing demand of circuit and wiring diagram for automotive and electronics on internet based on different uses such as electronic hobbyists, students, technicians and engineers than we decided to provide free circuit and wiring diagram base on your needed.
To find circuit and wiring diagram now a day its easy. E-learning through internet as a right place to search an exact circuit and wiring diagram of your choice and it's much fun and knowledgable. On internet you will find thousands of electronic circuit diagrams some are very good designed and some are not. So you have to modify them to make them according to your needs but some circuits are ready to make and require no changes.
There are many categories of circuit and wiring diagrams like automotive, audio circuits, radio & RF circuits, power supply circuits, light circuits, telephone circuits, timer circuits, battery charger circuits etc. There are many types of circuit and wiring diagrams some are very easy to build and some are very complicated, some are so small and some contain huge list of parts.
We provides free best quality and good designed schematic diagrams our diagrams are free to use for all electronic hobbyists, students, technicians and engineers. We also provides a full educational system to students new to electronics. If you are new to electronics you are a student or a electronic hobbyist and want to increase your knowledge in electronics or want to understand electronics in a very easy way so this is the right place for you we provide electronics beginner guide tutorials to easily understand complicated electronic theory. Our mission is to help students and professionals in their field.