Many familiar mechanical systems such as engines, powertrains and gearboxes generate rotational motion and transmit torque, movement, speed, and acceleration from one place to another. Thus these systems are significant sources of rotational vibration.
Non-contact measurements help to cope with undesired vibrations. Due to their flexibility, laser vibrometers are utilized in the R&D process, but are also a good tool for troubleshooting.
Laser vibrometry covers the three main applications:
- Torsional vibrations in shafts
- Bending vibrations in shafts
- Axial deflection shape measurement on rotors
This example shows the PSV-3D is capable of measuring torsional motion of a non-spinning shaft. The shaft in this example is a solid bar that is just over 2 feet long (~65 cm) and about 1 inch (2.5 cm) in diameter. It is fixed at one end and is free at the other end. A bracket is mounted on the free end, and a piezo exciter is placed on it to introduce a torsional motion.
The free end of the shaft could have been supported to limit out-of-plane motion, but was intentionally left unsupported to show the measurement can be accomplished with the same fidelity if there is no out-of-plane motion (as can be seen close to the fixed end), or a small out-of-plane motion (as can be seen closer to the unfixed end).