Introduction Digital force Gauge Piezoelectric sensor Strain Gauge sensor Mechanical force Gauge Scale spring References

1. Force Sensors
Done By Ahmad Taweel
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2. Outline
• Introduction
• Digital force Gauge
• Piezoelectric sensor
• Strain Gauge sensor
• Mechanical force Gauge
• Scale spring
• References
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3. Sensor
• A sensor is an object whose purpose is to detect
events or changes in its environment, and then
provide a corresponding output.
• Sensors typically use electrical or optical signals
as output
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4. Force gauge
• A force gauge is a small measuring instrument
used to measure the force during a push or pull
test
• There are two kinds of force gauges today:
Mechanical and Digital force gauges
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5. Digital force gauges
• Piezoelectric Sensor
• Strain gauge Sensor
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6. Piezoelectric Sensor
• History
• Definition
• Mechanism
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7. History
• Piezoelectric effect was first proven in 1880 by the
French Physicist brothers Pierre and Jacques Curie
• In the 1950s manufacturers begin to use the
piezoelectric effect
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8. Definition
• The word “piezoelectricity” is derived from a Greek
word “pizo” or “piezein” which means to squeeze or
press
• A piezoelectric sensor: is a device that uses the
piezoelectric effect to measure changes in pressure,
acceleration, temperature, strain, or force by
converting them to an electrical charge
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10. Mechanism (1/2)
1. The charges in a
piezoelectric crystal are
exactly balanced
2. The effects of the
charges exactly cancel
out, leaving no net charge
on the crystal faces
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11. Mechanism (2/2)
3. If crystal is
squeezed, the charges
are forced to be out of
balance
4. By squeezing the
crystal, a voltage is
produced across its
opposite faces—and
that's piezoelectric
effect
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12. Strain Gauge Sensor
• History
• Definition
• Mechanism
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13. History
• Invented by Edward E. Simmons and Arthur C.
Ruge in 1938
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14. Definition
• A strain gauge is a device used to measure strain
on an object
• Strain can be related to stress, force
• As the foil is subjected to force, the resistance
of the foil changes in a defined way
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16. • Initial State:
• No compression
• No extension
• Resistance zero
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Mechanism (1/3)

17. Mechanism (2/3)
• If a strip of conductive
metal is stretched, it will
result in an increase of
electrical resistance
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18. Mechanism (3/3)
• If a strip of conductive
metal is broaden and
shorten, it will result in a
decrease of electrical
resistance
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19. Mechanical force gauges
• Spring scale
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20. History
• The first spring balance was made around 1770
by Richard Salter of Bilston.
• In 1838 they obtained the spring balance patent
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21. Definition (1/2)
• A spring scale is a type of weighing
scale
• It consists of:
• Spring fixed at one end
• Hook to attach an object at the other
• The scale markings are equally spaced
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22. Definition (2/2)
• Spring balances come in different sizes
• Small scales that measure newton will have a less firm
spring
• Larger ones that measure tens, hundreds or thousands
of newton or even more depending on the scale of newton
used (5000-8000)
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23. Mechanism
• Measure only weight
• A spring scale will only read correctly in a frame
of reference
• It works by Hooke's Law
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25. References
• https://en.m.wikipedia.org/wiki/Force_gauge
• http://www.slideshare.net/researcher1234/ferroe
lectric-and-piezoelectric-materials
• https://en.wikipedia.org/wiki/Piezoelectric_sensor
• https://en.m.wikipedia.org/wiki/Strain_gauge
• https://en.m.wikipedia.org/wiki/Spring_scale
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26. Thank You
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