Hingeless, large-throw negative stiffness structure

• US 10,344,822 B2
• Filed: 11/27/2017
• Issued: 07/09/2019
• Est. Priority Date: 12/09/2014
• Status: Active Grant

• Current Assignee: HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: HRL Laboratories LLC (The Boeing Co.)
• Inventors: Churchill, Christopher B., Shahan, David W., McKnight, Geoffrey P., Herrera, Guillermo A.
• Primary Examiner(s): Siconolfi, Robert A.
• Assistant Examiner(s): Aung, San M
• Application Number:
  US15/823,374
• Publication Number:
  US 20180080521A1
• Time in Patent Office: 589 Days
• Field of Search: 267 47, 188378
• CPC Class Codes: F16F 15/073 using only leaf springs
• CPC Class Codes: F16F 2228/063 Negative stiffness
• CPC Class Codes: F16F 3/02 with springs made of steel or of other material having low internal friction

Abstract

A negative stiffness structure for vibration isolation, shock mitigation, and/or signal processing includes a flexible tensile member and a curved compressive member. A first end of the tensile member is attached to a first structure. A first end of the curved compressive member is coupled to a first structure and a second end of the curved compressive member is coupled to a second end of the flexible tensile member. A length of the tensile member is greater than a length of the compressive member. A tip of the negative stiffness structure is configured to exhibit a negative stiffness mechanical response to a load applied to the tip. The negative stiffness mechanical response acts in a direction orthogonal to the length of the tensile member.

Claims

1. A negative stiffness structure, comprising:

at least one flexible tensile member having a first end and a second end;

an actuator coupled to the first end of the at least one flexible tensile member; and

first and second curved compressive members each having a first end and a second end, the first ends coupled to a structure, the second ends coupled to the second end of the flexible tensile member, wherein

a length of the at least one flexible tensile member is greater than a length of each of the first and second curved compressive members,

the first curved compressive member is curved in a first direction and the second curved compressive member is curved in a second direction opposite the first direction,

a tip of the negative stiffness structure is configured to exhibit a mechanical response when a load is applied to the tip, and

the actuator is configured to change tension applied to the at least one flexible tensile member or change an effective length of the at least one flexible tensile member to change a compressive load on the first and second curved compressive members and vary the mechanical response of the tip.

5. The negative stiffness structure of claim 1, wherein the at least one flexible tensile member is selected from the group consisting of a beam, a rope, a cable, a rod, a chain, or a belt.

2. A negative stiffness structure, comprising:

at least one flexible tensile member having a first end and a second end;

an actuator coupled to the first end of the at least one flexible tensile member; and

first and second curved compressive members each having a first end and a second end, the first ends coupled to a structure, the second ends coupled to the second end of the flexible tensile member, wherein

a length of the tensile member is greater than a length of each of the first and second curved compressive members,

the first curved compressive member is curved in a first direction and the second curved compressive member is curved in a second direction opposite the first direction,

a tip of the negative stiffness structure is configured to exhibit a mechanical response when a load is applied to the tip,

the actuator is configured to vary the mechanical response of the tip, and

the actuator is a toothed gear.

3. A negative stiffness structure, comprising:

at least one flexible tensile member having a first end and a second end;

an actuator coupled to the first end of the at least one flexible tensile member; and

first and second curved compressive members each having a first end and a second end, the first ends coupled to a structure, the second ends coupled to the second end of the flexible tensile member, wherein

a length of the tensile member is greater than a length of each of the first and second curved compressive members,

the first curved compressive member is curved in a first direction and the second curved compressive member is curved in a second direction opposite the first direction,

a tip of the negative stiffness structure is configured to exhibit a mechanical response when a load is applied to the tip,

the actuator is configured to vary the mechanical response of the tip, and

the actuator is a pulley.

4. A negative stiffness structure, comprising:

at least one flexible tensile member having a first end and a second end;

an actuator coupled to the first end of the at least one flexible tensile member; and

first and second curved compressive members each having a first end and a second end, the first ends coupled to a structure, the second ends coupled to the second end of the flexible tensile member, wherein

a length of the tensile member is greater than a length of each of the first and second curved compressive members,

the first curved compressive member is curved in a first direction and the second curved compressive member is curved in a second direction opposite the first direction,

a tip of the negative stiffness structure is configured to exhibit a mechanical response when a load is applied to the tip,

the actuator is configured to vary the mechanical response of the tip, and

the actuator is a clamp configured to clamp the tensile member at a plurality of positions along the length of the tensile member.

6. A negative stiffness structure, comprising:

at least one flexible tensile member having a first end and a second end;

an actuator coupled to the first end of the at least one flexible tensile member; and

first and second curved compressive members each having a first end and a second end, the first ends coupled to a structure, the second ends coupled to the second end of the flexible tensile member, wherein

a length of the tensile member is greater than a length of each of the first and second curved compressive members,

the first curved compressive member is curved in a first direction and the second curved compressive member is curved in a second direction opposite the first direction,

a tip of the negative stiffness structure is configured to exhibit a mechanical response when a load is applied to the tip,

the actuator is configured to vary the mechanical response of the tip, and

the negative stiffness structure has a throw of about 40% of a length between the first ends and the second ends of the compressive members.