Typical turboprop noise spectra exhibit a series of characteristic peaks which are directly related to the product of propeller rpm and number of propeller blades. These blade passage frequencies contribute significantly to the overall sound pressure level both outside and inside the aircraft. Their contribution to cabin noise is usually reduced by appropriately adjusted mass dampers. However, since the engine rpm varies for different flight stages, any fixed eigenfrequency absorber will merely be a sub-optimal compromise.
The Tunable Vibration Absorber (TVA) introduced in this article has a variable resonant frequency which enables an adaptation to different flight phases providing largely improved performance. Frequency tuning is achieved through a piezo-electric stack actuator, which applies a pressure force to a pair of leaf springs thus reducing their effective bending stiffness.
Among the main advantages of this particular approach are a static control signal and low power consumption. To enable a light-weight construction the components which generate the pressure loading are incorporated into the oscillating mass.
The TVA allows to cover a wide frequency range using only a single device. Additionally, it features damping control capability and optional active multi-mode operation. Structural-acoustic simulations have indicated a noise reduction potential of approximately 10 dB.
This article gives a short overview of different tuneable vibration absorber concepts, lines out the theoretical background of the proposed approach, discusses the general components layout and describes the experimental verification of a prototype TVA for the Airbus A400M.
[1]
Robert E. Roberson,et al.
Synthesis of a nonlinear dynamic vibration absorber
,
1952
.
[2]
A. D. S. Barr,et al.
The Autoparametric Vibration Absorber
,
1972
.
[3]
J. Ormondroyd.
Theory of the Dynamic Vibration Absorber
,
1928
.
[4]
Horst Irretier.
Grundlagen der Schwingungstechnik 2
,
2001
.
[5]
Eugene Sevin,et al.
On the Parametric Excitation of Pendulum-Type Vibration Absorber
,
1961
.
[6]
A. R. Beard,et al.
Adaptive tuned vibration absorbers: Tuning laws, tracking agility, sizing, and physical implementations
,
1994
.
[7]
Paul H. Wirsching,et al.
Minimal structural response under random excitation using the vibration absorber
,
1973
.
[8]
David G. Jones,et al.
Vibration and Shock in Damped Mechanical Systems
,
1968
.
[9]
J. Hunt.
Dynamic vibration absorbers
,
1979
.
[10]
Hans Peter Monner,et al.
Piezo Tuneable Vibration Absorber (PTVA) for Turboprop Aircraft
,
2006
.
[11]
Paolo Gardonio,et al.
Review of Active Techniques for Aerospace Vibro-Acoustic Control
,
2002
.
[12]
J. C. Snowdon.
Platelike Dynamic Vibration Absorbers
,
1975
.
[13]
Stephen P. Timoshenko,et al.
Vibration problems in engineering
,
1928
.
[14]
J. Hunt,et al.
The broadband dynamic vibration absorber
,
1982
.
[15]
K. Nakamoto,et al.
Vibration Control of Shallow Shell Structures Using a Shell-Type Dynamic Vibration Absorber
,
1998
.