Sintered viscoelastic particle vibration damping treatment

• US 6,381,196 B1
• Filed: 10/26/2000
• Issued: 04/30/2002
• Est. Priority Date: 10/26/2000
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Drake, Michael L., Stack, Christopher F., Hein, Kenneth D.
• Primary Examiner(s): Pihulic, Daniel T
• Application Number:
  US09/696,702
• Time in Patent Office: 551 Days
• Field of Search: 367/1, 252/62, 181/207
• US Class Current: 367/1
• CPC Class Codes: F16F 9/30 with solid or semi-solid material, e.g. pasty masses, as damping medium in devices where rotary elements are damped by viscous shear effect only, any throttling effect being immaterial F16F9/12; where members moving with a rotating system are being damped F16F15/16

Abstract

A damping entity comprises a matrix of plural viscoelastic particles, typically between 0.05 in and 0.5 in in size, which slightly and fixedly contact one another. The particles generally bond with each other at their contact zones and approximately correspondingly therewith. Suitable particle viscoelasticities are defined by either or both of: (i) an approximate shear modulus range between 10 p.s.i. and 100,000 p.s.i.; and, (ii) an approximate loss factor range between 0.05 and 1.5. The particles which describe the matrix can be essentially identical in terms of size, shape and material composition, or can vary among themselves in one or more of these respects. These properties can be selected uniformly or more or less nonuniformly among the particles of a particular matrix in order to imbue the matrix with desired damping characteristics, e.g., in terms of frequency ranges and temperature ranges. The cumulative matrix mass resonates at “tuned” frequencies and thereby dampens the vibrating structure to which it is applied.

Claims

1. A passive vibration damping device comprising plural viscoelastic particles which generally cohere with one another, wherein at least substantially every said particle is characterized by:

adherent communication with at least one other said particle;

adjacency to at least one separation between said particle and at least one other said particle; and

at least one of;

an approximate shear modulus in the range between about 10 p.s.i. and about 100,000 p.s.i. inclusive; and

an approximate loss factor in the range between about 0.05 and about 1.5 inclusive.

2. A device as recited in claim 1, wherein said adherent communication includes:

a contact region between two said particles; and

a bond region therebetween which is at least approximately commensurate with said contact region.

3. A device as recited in claim 1, wherein at least substantially every said particle is characterized by size in the range between about 0.05 inches and about 0.5 inches inclusive.

4. A device as recited in claim 1, wherein at least substantially every said particle is characterized by an at least approximately spherical shape.

5. A device as recited in claim 4, wherein at least substantially every said particle is characterized by at least approximately the same diameter.

6. A device as recited in claim 4, wherein at two said particles are characterized by different diameters.

7. A device as recited in claim 1, wherein at least substantially every said particle is characterized by an approximate shape selected from the group consisting of spherical, oblate spherical, rectangular parallelepiped.

8. A device as recited in claim 1, wherein at least one said particle includes a core and a plurality of projections, said core being characterized by an at least approximately spherical shape.

9. A device as recited in claim 1, wherein at least one said particle is characterized by curvlinearity.

10. A device as recited in claim 1, wherein at least one said particle is characterized by rectilinearity.

11. A device as recited in claim 1, wherein at least substantially every said particle is characterized by:

at least approximately the same size;

at least approximately the same shape; and

at least approximately the same material composition.

12. A device as recited in claim 1, wherein:

at least substantially every said particle is characterized by at least approximately the same size and at least approximately the same shape; and

at least two said particles are characterized by different material compositions.

13. A device as recited in claim 1, wherein:

at least substantially every said particle is characterized by at least approximately the same size;

at least two said particles are characterized by different shapes; and

at least substantially every said particle is characterized by the same material composition.

14. A device as recited in claim 1, wherein:

at least two said particles are characterized by different sizes; and

at least substantially every said particle is characterized by at least approximately the same shape and at least approximately the same material composition.

15. A device as recited in claim 1, wherein:

at least substantially every said particle is characterized by at least approximately the same size;

at least two said particles are characterized by different shapes; and

at least two said particles are characterized by different material compositions.

16. A device as recited in claim 1, wherein:

at least two said particles are characterized by different sizes;

at least two said particles are characterized by different shapes; and

at least substantially every said particle is characterized by at least approximately the same material composition.

17. A device as recited in claim 1, wherein:

at least two said particles are characterized by different sizes;

at least substantially every said particle is characterized by at least approximately the same shape; and

at least two said particles are characterized by different material compositions.

18. A device as recited in claim 1, wherein:

at least two said particles are characterized by different sizes;

at least two said particles are characterized by different shapes; and

at least two said particles are characterized by different material compositions.

19. A device as recited in claim 1, wherein at least substantially every said particle is characterized an approximate shear modulus in the range between about 10 p.s.i. and about 100,000 p.s i. inclusive.

20. A device as recited in claim 1, wherein at least substantially every said particle is characterized by an approximate loss factor in the range between about 0.05 and about 1.5 inclusive.

21. A device as recited in claim 1, wherein at least substantially every said particle is characterized by both:

an approximate shear modulus in the range between about 10 p.s.i. and about 100,000 p.s.i. inclusive; and

an approximate loss factor in the range between about 0.05 and about 1.5 inclusive.

22. A method for effectuating passive damping of an object, said method comprising:

(a) providing a device comprising plural viscoelastic particles which generally cohere with one another, at least substantially every said particle being characterized by;

adherent communication with at least one other said particle;

adjacency to at least one separation between said particle and at least one other said particle; and

at least one of;

an approximate shear modulus in the range between about 10 p.s.i. and about 100,000 p.s.i. inclusive; and

an approximate loss factor in the range between about 0.05 and about 1.5 inclusive; and

(b) coupling said device with said object.

23. A method for effectuating passive damping as recited in claim 22, wherein at least substantially every said particle is characterized by size in the range between about 0.05 inches and about 0.5 inches inclusive.

24. A method for effectuating passive damping as recited in claim 22, wherein said providing a device includes making said device, and wherein said making said device includes:

placing said particles in a mold; and

causing said particles to generally cohere with one another.

25. A method for effectuating passive damping as recited in claim 22, wherein said causing said particles to generally cohere includes, after placing said particles in a mold, applying heat and thereby sintering said particles.

26. A method for effectuating passive damping as recited in claim 22, wherein said causing said particles to generally cohere includes, after placing said particles in a mold, dousing said particles with at least one particle-softening solvent.

27. A method for effectuating passive damping as recited in claim 22, wherein said causing said particles to generally cohere includes, after placing said particles in a mold, dousing said particles with at least one evaporable solvent, and applying heat and thereby evaporating said at least one evaporable solvent.

28. A method for effectuating passive damping as recited in claim 22, wherein said causing said particles to generally cohere includes:

before placing said particles in a mold, coating said particles with a heat-curing adhesive; and

after placing said particles in a mold, applying heat and thereby curing said adhesive.

29. A method for effectuating passive damping as recited in claim 22, wherein said coupling said device with said object includes coupling said device with said object so that, when said object is subjected to vibrational excitation, said device resonates at at least one frequency range so as to at least partially counteract, in tuned fashion, at least one corresponding frequency range of said vibrational excitation.

30. A method for effectuating passive damping as recited in claim 22, wherein said coupling said device with said object includes coupling said device with said object so that, when said object is subjected to vibrational excitation, said device resonates at at least one frequency in at least one temperature range so as to at least partially counteract, in tuned fashion, at least one corresponding frequency range in at least one corresponding temperature range of said vibrational excitation.

31. A method for making a device suitable for passively damping a structure, said method comprising:

(a) providing plural viscoelastic particles, each said particle being characterized by at least one of;

an approximate shear modulus in the range between about 10 p.s.i. and about 100,000 p.s.i. inclusive; and

an approximate loss factor in the range between about 0.05 and about 1.5 inclusive;

(b) placing said particles in a mold; and

(c) causing said particles to generally cohere with one another.

32. A method for making as recited in claim 31, wherein at least substantially every said particle is characterized by size in the range between about 0.05 inches and about 0.5 inches inclusive.

33. A method for making as recited in claim 31, wherein said causing said particles to generally cohere includes, after placing said particles in a mold, applying heat so as to sinter said particles.

34. A method for making as recited in claim 31, wherein said causing said particles to generally cohere includes, after placing said particles in a mold, dousing said particles with at least one particle-softening solvent.

35. A method for making as recited in claim 31, wherein said causing said particles to generally cohere includes, after placing said particles in a mold:

dousing said particles with at least one evaporable solvent; and

applying heat so as to evaporate said at least one evaporable solvent.

36. A method for making as recited in claim 31, wherein said causing said particles to generally cohere includes:

before placing said particles in a mold, coating said particles with a heat-curing adhesive; and

after placing said particles in a mold, applying heat so as to cure said adhesive.