Passive structures with high stiffness and high damping properties

• US 9,376,807 B2
• Filed: 08/21/2012
• Issued: 06/28/2016
• Est. Priority Date: 08/23/2011
• Status: Active Grant

• Current Assignee: Teledyne Scientific & Imaging, LLC (Teledyne Technologies Incorporated)
• Original Assignee: Teledyne Scientific & Imaging, LLC (Teledyne Technologies Incorporated)
• Inventors: Chen, Bing-Chung, Gould, Kyle D., Liao, Ten-Luen
• Primary Examiner(s): Schwartz, Christopher
• Application Number:
  US13/591,009
• Publication Number:
  US 20130047523A1
• Time in Patent Office: 1,407 Days
• Field of Search: 267159-162, 267/164, 248/618, 188/378, 521/671
• US Class Current: 1/1
• CPC Class Codes: B64C 1/062 specially adapted to absorb crash loads
• CPC Class Codes: E02B 2017/0091 Offshore structures for wind turbines
• CPC Class Codes: E04H 9/0215 involving active or passive dynamic mass damping systems
• CPC Class Codes: F16F 7/104 the inertia member being resiliently mounted F16F7/1022 takes precedence

Abstract

A passive structural system includes a structural element which may be subjected to energy which gives rise to vibration in the element. At least one bi-stable sub-structure is coupled to the element. Each bi-stable sub-structure has two stable equilibrium states between which the sub-structure can physically transition when subjected to a sufficient amount of energy which gives rise to vibration in the element, with each bi-stable sub-structure arranged to dissipate at least a portion of the energy and thereby damp the vibration in the structural element when it transitions from one equilibrium state to the other. The passive structural system may also be intentionally mistuned such that when subjected to energy which gives rise to vibration, the vibration energy is substantially confined to localized regions within the system. The bi-stable structures are then located in the localized regions and arranged to dissipate the localized vibration energy.

Claims

1. A passive structural system, comprising:

a structural element which may be subjected to energy which gives rise to vibration in said structural element;

at least one bi-stable sub-structure coupled to said structural element, each of said bi-stable sub-structures having two stable equilibrium states between which said sub-structure can physically transition when subjected to a sufficient amount of said energy which gives rise to vibration in said structural element, each of said bi-stable sub-structures arranged to dissipate at least a portion of said energy and thereby damp the vibration in said structural element when it physically transitions from one of said equilibrium states to the other,

wherein each of said bi-stable sub-structures comprises a movable element which has an associated mass and may be in either of said two stable equilibrium states or transitioning between said states, the inertia of said mass when subjected to said energy which gives rise to vibration in said structural element causing said bi-stable sub-structure to transition from one of said stable equilibrium states to the other,

wherein each of said stable equilibrium states has an associated equilibrium position relative to a nominal center position between said equilibrium positions, each of said bi-stable sub-structures having an associated relationship between reaction force and the displacement between said bi-stable sub-structure and said nominal center position and arranged such that when said bi-stable sub-structure is acted upon by a force, said reaction force is in the same direction as the action force and the sub-structure enters a negative stiffness region where the slope of the reaction force over displacement is negative.

2. The system of claim 1, further comprising one or more additional masses coupled to said movable element, said bi-stable sub-structure arranged such that said associated mass consists of the inherent mass of said movable element plus the one or more additional masses coupled to said movable element.

3. The system of claim 2, wherein one of said additional masses is coupled to the point of said movable element which exhibits the greatest amount of displacement when said bi-stable sub-structure transitions from one of said equilibrium states to the other.

4. The system of claim 1, wherein said structural element is a hollow structure having an associated longitudinal axis, each of said bi-stable sub-structures comprising an buckled column which spans the hollow interior of said structural element and is oriented perpendicular to said tube'"'"'s longitudinal axis.

5. The system of claim 4, wherein each of said buckled columns is a constrained, buckled column.

6. The system of claim 1, said bi-stable sub-structure arranged such that said associated mass consists solely of the inherent mass of said movable element.

7. The system of claim 1, wherein each of said movable elements is dome-shaped or arch-shaped.

8. The system of claim 1, wherein said movable elements comprise silicone rubber, composite laminates, or flexible metal.

9. The system of claim 1, wherein each of said bi-stable sub-structures comprises a movable element comprising a bi-stable composite laminate plate.

10. The system of claim 1, wherein a plurality of said bi-stable sub-structures are coupled to said structural element periodically.

11. The system of claim 1, wherein each of said bi-stable sub-structures has associated characteristics which govern the conditions under which said bi-stable sub-structure transitions from one of said equilibrium states to the other, said characteristics tailored to provide a desired amount of damping for said structural element.

12. The system of claim 1, wherein said passive structural system is intentionally mistuned such that when said passive structural system is subjected to energy that gives rise to vibration in said structural system, said vibration energy is substantially confined to localized regions within said structural system, said bi-stable structures located in said localized regions and arranged to dissipate said localized vibration energy.

13. A passive structural system, comprising:

a structural element;

periodic appendage sub-structures attached to said structural element and mistuned such that when said structural system is subjected to energy that gives rise to vibration in said structural system, said vibration energy is substantially confined to localized regions within said structural system; and

damping elements in said localized regions arranged to dissipate said localized vibration energy,

wherein said structural element is a hollow tube-shaped structure, said damping elements comprising bi-stable sub-structures located within and along the axial length of said tube at respective ones of said localized regions, said bi-stable sub-structures having two equilibrium states and arranged to transition from one equilibrium state to the other when subjected to said vibration energy and thereby dissipate at least a portion of said vibration energy,

wherein each of said bi-stable sub-structures comprises a movable element which has an associated mass and may be in either of said two stable equilibrium states or transitioning between said states, the inertia of said mass when subjected to said energy which gives rise to vibration in said structural system causing said bi-stable sub-structure to transition from one of said stable equilibrium states to the other.

14. The system of claim 13, wherein said periodic appendage sub-structures are rings that are coupled to and encircle said structural element.

15. The system of claim 14, wherein one of said damping elements comprises a layer between each of said encircling rings and said structural element, each of said layers comprising a coupling elastic and damping material and arranged to couple a respective encircling ring to said structural element.

16. The system of claim 15 wherein said layers have respective material properties, at least one of which varies from layer to layer, said variance resulting in at least a portion of said mistuning.

17. The system of claim 16, wherein said material property which varies from layer to layer comprises stiffness and/or damping coefficient.

18. The system of claim 15, wherein said encircling rings are distributed along the axial length of said tube, said encircling rings arranged to move along said tube'"'"'s longitudinal axis when subjected to vibration and thereby dissipate at least a portion of said vibration energy.

19. The system of claim 14, wherein said encircling rings have respective parameters, at least one of which varies from ring to ring, said variance resulting in at least a portion of said mistuning.

20. The system of claim 19, wherein said parameters comprise encircling ring diameter and/or encircling ring weight.

21. The system of claim 14, wherein said encircling rings are distributed at equal intervals along the axial length of said tube.

22. The system of claim 14, wherein said encircling rings are distributed at unequal intervals along the axial length of said tube, said unequal intervals resulting in at least a portion of said mistuning.

23. The system of claim 13, wherein each of said bi-stable sub-structures comprises an buckled column which spans the hollow interior of said tube and is oriented perpendicular to said tube'"'"'s longitudinal axis.

24. The system of claim 23, wherein each of said buckled columns is a constrained, buckled column.

25. The system of claim 13, wherein each of said bi-stable sub-structures comprises a pair of buckled columns which intersect to form an X-shaped pattern, each of said buckled columns arranged to span the hollow interior of said tube and oriented perpendicular to said tube'"'"'s longitudinal axis.

26. The system of claim 25, wherein each of said associated masses comprises a concentrated mass at a respective one of the intersections of said buckled columns, the motion of said buckled columns and said concentrated masses during said transitions between said equilibrium states dissipating at least a portion of said vibration energy.

27. The system of claim 13, further comprising a structural link which couples said periodic appendage sub-structures together.

28. The system of claim 27, wherein said periodic appendage sub-structures are rings that are coupled to and encircle said structural element, said structural link coupling said encircling rings together.

29. The system of claim 27, said at least one of said damping elements comprising bi-stable sub-structures located along the axial length of said tube at respective localized regions within said tube, said structural link coupling said encircling bi-stable sub-structures together.