The vibration of a cantilever beam is to be controlled using the setup shown in
ID: 2083787 • Letter: T
Question
The vibration of a cantilever beam is to be controlled using the setup shown in Figure Q2. A piezoelectric accelerometer is mounted on the beam tip, and a surface-mounted piezoelectric actuator is mounted near the built-in end of the beam. Both the sensor and actuator are made from the piezoelectric material Lead Zirconate Titanate. (a) (i) Draw the unit cell for a Lead Zirconate Titanate (PZT) crystal, in its 'unpoled' state. Clearly label the location of the lead (Pb), Oxygen (O) and Titanium or Zirconium (Ti/Zi) ions. (ii) Indicate on your diagram the new position for the Zi/Ti ion after the poling operation. (iii) Briefly explain how the movement of the Zi/Ti ion can lead to the material being used as a sensor and an actuator. (b) Describe, with the aid of a suitable diagram, how piezoelectric material can be used to make accelerometers such as that shown in Figure Q2. List one advantage and one disadvantage of piezoelectric accelerometer sensors compared to alternative sensor technologies. (c) The beam shown in Figure Q2 must operate at a temperature of 250 degree C. Briefly explain which type of device would be most appropriate: a charge-amplifer type accelerometer, or an integrated-circuit type accelerometer.Explanation / Answer
Solution :
b) Advantage: Piezoelectric accelerometer sensors are used for measuring and recording dynamic changes in mechanical variations like shock and vibration and also they convert one form of energy into other and provide an electrical signal in response to a quantity, property, condition that is being calculated.
Disadvantage: They are high resistance devices so they can take high stray voltages in the wires and also they can crack if are overstressed
c) A charge amplifier type accelerometer must be suitable to operate above structure at temperature of 2500 C
because they are flexible to adjust electrical output characteristics properly whereas this case is not followed in an integrated circuit accelerometer because of loss of resolution.
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