Hingeless Negative Stiffness Structure for Vibration Isolation
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Solution Overview
Problem
Existing negative stiffness mechanisms incorporate pins, hinges, or sliding joints, increasing complexity and cost, and often have a limited range of motion and short useful life due to friction and wear, with a small beam length to throw ratio.
Innovation Solution
A hingeless negative stiffness structure comprising flexible tensile and curved compressive members, where the tensile member is longer than the compressive members, and an actuator adjusts tension or effective length to vary the mechanical response, allowing for a broader range of motion and reduced friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pins, hinges, or sliding mechanical joints are incorporated into negative stiffness mechanisms, then the mechanism can achieve negative stiffness response, but the complexity and cost of the mechanism increases
Solution Approach 1:
The patent removes pins, hinges, and sliding mechanical joints from the negative stiffness mechanism, extracting the problematic connection elements that cause complexity and cost increases while maintaining the essential negative stiffness functionality through direct coupling of beam elements
Solution Approach 2:
The patent combines multiple separate components (pins, hinges, sliding joints) into a unified beam structure where connections are integrated directly into the beam geometry, eliminating the need for separate connection elements and reducing overall mechanism complexity
2Force
If bearing components are included in negative stiffness mechanisms, then the mechanism can support loads, but the cost increases and friction and wear increase, limiting useful life
Solution Approach 1:
The patent removes bearing components from the mechanism, extracting the source of friction and wear that limit useful life, while maintaining load support capabilities through the structural design of the beam elements themselves
Solution Approach 2:
The patent replaces the mechanical bearing system with a structural beam design that inherently supports loads through its geometry and material properties, eliminating the need for separate bearing components and their associated friction and wear issues
3Ease of operation
If traditional negative stiffness mechanisms are designed with standard beam dimensions, then the structure is simple to manufacture, but the range of motion is limited with a beam length to throw ratio of approximately 20:1 or 10:1
Solution Approach 1:
The patent changes the beam length to throw ratio parameter from traditional values of 20:1 or 10:1 to a new ratio greater than 10:1, enabling increased range of motion while maintaining manufacturing feasibility through the hingeless design that simplifies the manufacturing process
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The structure achieves a tunable negative stiffness response with a larger range of motion and reduced wear, enhancing applications like vibration isolation and shock mitigation without the need for costly bearings or hinges.
Implementation Method 1
A first end of first end of the curved compressive member is coupled to a second structure and a second end of the curved compressive member is coupled to a second end of the flexible tensile member
Implementation Method 2
The at least one curved compressive member may include a stack of a series of curved compressive members. The at least one flexible tensile member may include a series of tensile members
Implementation Method 3
A first end of the flexible tensile member is coupled to a first structure. A length of the flexible tensile member is greater than a length of the curved compressive member
Data Source
AI summary
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.