Note Technique Arma_en

Technical Note AR02-290409

Applying ARMA for Transfer function without impact Hammers Transfer functions measurement is a powerful technique allowing the identification of resonance frequencies of a structure. If an excitation coincides with one of these frequencies, an exponential amplification of the vibration is observed, with a negativ effect both on the operation of the equipment and its useful life. The impact technique is the simplest and easiest to implement. It involves measuring -with an accelerometer- the response of the structure studied to a known excitation- impact hammer equipped with a force sensor. The transfer function is calculated by dividing

However, for several reasons, it can be difficult to measure properly the excitation of the structuresometimes even impossible-. In these cases, the use of ARMA technique allows to bypass this limitation and to trace the transfer function without the impact hammer signal. The ARMA technique is tested on the fellowing testrig:

The transfer function measured on the shaft in the vertical direction with the impact hammer is compared to the one calculated with ARMA.

www.betavib.com