Method and apparatus using a piezoelectric film for active control of vibrations
AssigneeMassachusetts Institute of Technology
InventorJames E. Hubbard, Jr.
Life of this patent
Estimating the term…
Abstract
A method and apparatus is disclosed in which a piezoelectric film is used to control or dampen vibrations in a mechanical system. Voltage of proper amplitude and phase is fed across the piezoelectric film to induce strain in the film of appropriate phase, amplitude and frequency to dampen beam vibrations of the mechanical system. The film may be applied directly to the mechanical system or an intermediate viscoelastic layer may be provided. Various control functions are described for determining the correct voltage to be applied to the film.
Claims26
A method of damping vibrations in a member, comprising the steps of:
- a. applying a distributed parameter film means of piezoelectric material for sensing and damping vibration in said member in cooperative relationship with the surface of said member and;
- b. sensing, with said film means, vibrations in said member and producing with said film means a first electrical signal proportional to said sensed vibration;
- c. applying to said film means a second electrical signal derived from said first signal of proper amplitude frequency and phase to dampen said vibrations in said member.
A method of damping mechanical vibrations of a plurality of modes in a mechanical member, comprising the steps of:
- a. applying a non-spatially discrete piezoelectric film means for detecting and damping vibrations in a very large number of vibrational modes in cooperative relationship with the surface of the member in which vibrations are to be damped;
- b. attaching strain detection means to said member for converting the detected mechanical modes of vibration to a vibration signal proportional to said modes of vibration;
- c. amplifying the vibration signal;
- and
- d. coupling to the piezoelectric film means a proportional signal which is proportional to the amplified vibration signal.
An apparatus for damping vibrations in a mechanical member, comprising:
- a. a viscoelastic material and
- b. a distributed parameter film means of piezoelectric material mechanically cooperating with a member such that an electrical signal is applied to the film means and corresponding mechanical strain signals are induced in the member.
An apparatus for damping vibrations in a mechanical system, comprising:
- a. a distributed parameter film means of piezoelectric material for sensing and damping vibration in said system, mechanically cooperating with a member such that an electrical signal is applied to the film means and corresponding mechanical strain signals are induced in the member.
A method of damping vibrations in a mechanical member, comprising the steps of:
- a. applying a distributed parameter film means of piezoelectric material for sensing and damping vibrations in the mechanical member in cooperative relationship with the surface of the member in which vibrations are to be damped;
- b. attaching accelerometer means to said member for providing an acceleration signal proportional to the linear or angular acceleration of said member;
- c. integrating said acceleration signal to provide a member velocity signal;
- d. feeding back to the film means a negative feedback signal derived from said velocity signal to dampen vibrations in said member.
An apparatus for damping vibrations in a distributed parameter system, comprising:
- a. a piezoelectric film material constituting a distributed parameter controller mechanically cooperating with the system;
- means for applying a voltage signal to the film material at the proper frequency and phase and amplitude to induce a mechanical strain in the film material to dampen vibrations in said system.
Dependencies are inferred from the claim text.