A displacement transducer, also known as a linear displacement sensor, is a type of sensor used to measure the linear displacement or position of an object. Displacement transducers are commonly used in structural health monitoring to measure the motion and deformation of a structure under various loading conditions.
Displacement transducers can take many forms, but they all work by converting the linear motion or displacement of an object into an electrical signal that can be easily read and processed. The most common types of displacement transducers include:
- Linear variable differential transformers (LVDTs) which consist of a primary coil and two secondary coils.
- Linear potentiometers which consist of a resistive element and a sliding contact.
- Capacitive transducers which consist of two electrodes, one of which is fixed and the other of which is movable.
- Wire transducers are displacement sensors which use a wire on a rolling bin which coils up to measure distances.
- Laser transducers find the distance to a surface or reflex.
The output of displacement transducers is usually in the form of a voltage or current that is proportional to the displacement of the object being measured.
Displacement transducers are often used in conjunction with other types of sensors, such as accelerometers and strain gauges, to provide a more complete understanding of the behaviour of a structure under different loads.
- Measuring the displacement of a structure caused by changes in temperature or humidity.
- Measuring the displacement of a structure caused by loading from wind or waves.
- Measuring the displacement of a structure caused by earthquakes or other seismic activity.
- Measuring the displacement of a structure caused by the movement of the ground beneath it.
- Measuring the displacement of a structure caused by the movement of the structure itself, such as the expansion and contraction of bridges.
- Measuring displacements at expansions joints in bridges.
- Measuring displacements at bridge bearings.
- Measuring distance between bridge decks on bridges with multiple separate decks.
In particular, displacement sensors are used to measure the displacement of bridges, buildings, towers, dams, and other structures. By measuring the displacement of these structures, engineers can determine the overall health of the structure and identify potential issues or damage.