Investigating vibroacoustic sound emission of a clinically applied knee prosthesis

Identification and evaluation of sound generation of a knee prosthesis is a major part of the development of next-generation prostheses, as its noise emissions have multiple negative effects on both the user and the user’s environment.
This work focuses on the vibroacoustics of a clinically applied hydraulic knee prosthesis. Structural vibrations are induced by turbulent flow phenomena inside the encapsulated, passive hydraulic damping unit of the prosthesis under investigation.
Therefore, the frame of the prosthesis is investigated both experimentally and numerically, to better understand significant vibroacoustic emission mechanisms. Laser-Doppler vibrometry was used to obtain a modal representation of the structural dynamics of the prosthesis frame for a reproducible excitation source.
Furthermore, the acoustic near- and far-field based on the experimentally obtained structural vibrations is predicted using the boundary element solver NiHu.
Consequently, the presented methods cover a major part of the overall acoustic transfer path of sound in a complex encapsulated hydraulic system and provide a link to investigations on the flow acoustics inside the hydraulic system.