Vibrational analysis and diagnostics by means of laser triangulation sensor

Nowadays, vibrational analysis is one of the most exploited methods in order to understand the behavior of mechanical components, by means of modal testing, and to monitor their conditions, by means of vibrational diagnostics. This kind of analysis has usually been performed through acceleration measures and exists a truly rich literature about this. However, in the last years, the genuine methodologies based on acceleration measurement, e.g. through piezoelectric accelerometers, came into conflict with the industrial need for time reduction. The sensors used have to be easily removable in order to speed up the control operation, for example at the end of the productive line. In this scenario a valid solution is represented by the use of laser triangulation sensors that are able to measure the dynamic displacement without the contact with the component surface and consequently with very high decrement of the time needed to mount and unmount. This work is focused on a comparison of the results obtained by piezoelectric accelerometer and laser triangulation sensor both for vibrational analysis, i.e. experimental modal analysis and vibrational diagnostics of rotating machines. This paper highlights pros and cons of the contactless displacement analysis with respect to the accelerometer measurements.