Piezoelectric Force Sensor is a transducer that employs the piezoelectric effect for the measurement of force by transforming force into an electrical signal. It is the most common Dynamic Force Detector. Based upon the application needs, dynamic force can be measured as either: Compression, Tensile, or Torque force. Quartz Piezoelectric Force Sensors are recommended for dynamic force measurement applications.
When force is applied to this sensor, the quartz crystals generate an electrostatic charge proportional to the input force. This output is collected on the electrodes sandwiched between the crystals and is then either routed directly to an external charge amplifier or converted to a low impedance voltage signal within the sensor.
Discharge Time Constant (DTC) is defined as the time needed for a sensor or measuring system to discharge its signal to 37% of the original value from a step change of measurand. This is accurate in case of every piezoelectric sensor, whether the operation is force, pressure or vibration monitoring. The DTC of a system is directly linked to the low frequency monitoring capabilities of a system. In the case of force monitoring, it becomes extremely significant as it is frequently desired to carry out quasi-static measurements.
Features of Piezoelectric Dynamic Force Sensor
Measurements of dynamic oscillating forces, impactor high speed compression/tension under varying conditions may require sensors with special capabilities. Fast response, ruggedness, stiffness comparable to solid steel, extended ranges and the ability to also measure quasi-static forces are standard features associated with quartz piezoelectric force sensors. Following are the key features of piezoelectric force sensors:
- A piezoelectric force sensor is approximately as rigid as a comparably proportioned piece of solid steel. This stiffness and strength enables these sensors to be directly inserted into machines as part of their structure.
- Their rigidity bestows them with a high natural frequency, and their equivalent rapid rise time makes them ideal for measuring such rapid transient forces as those generated by metal-to-metal impacts and by high frequency vibrations.
- To make certain accurate measurement, the natural frequency of the sensing device must be considerably higher than the frequency to be measured. If the measured frequency comes close to the natural frequency of the sensor, measurement errors will result.
Applications of Piezoelectric Dynamic Force Sensor
- Measurement of spring or sliding friction forces
- Measurement of Compression and Tension
- Measurement of Clutch release forces
- Measurement of Peel strengths of laminates, labels, and pull tabs