Superelastic Multi-Axis Flexure for Payload Vibration Isolation
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Solution Overview
Problem
Current multi-axis flexures and rotational isolators used in sensor mounts and other payloads fail frequently due to high rotational stiffness and reduced tensile strength when scaled up, leading to increased costs and downtime, as they are unable to effectively absorb and mitigate vibrations and impact loads without failure.
Innovation Solution
The use of superelastic shape-memory alloys, such as Nitinol, in the radial supports of the multi-axis payload isolation device provides improved rotational flexibility and shock absorption, allowing for temporary translational movement to absorb impact loads without failing, while maintaining sufficient tensile strength for nominal operational loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the size of a flexure is increased to support larger payloads, then the payload capacity increases, but the rotational stiffness increases by approximately a power of three or four, making the flexure undesirably stiff rotationally
Solution Approach 1:
The patent applies parameter changes by transitioning from conventional steel materials to superelastic shape-memory alloys (such as Nitinol), fundamentally altering the material's mechanical properties. This material substitution enables the flexure to achieve low rotational stiffness while maintaining high tensile strength, resolving the scaling contradiction where larger dimensions typically increase rotational stiffness by a power of three or four.
Solution Approach 2:
The invention utilizes composite material properties by combining the superelastic characteristics of shape-memory alloys with the structural geometry of the flexure. The radial supports are constructed from these advanced materials to create a composite structure that simultaneously provides rotational flexibility and tensile strength, overcoming the limitations of homogeneous conventional materials when scaled up.
2Force
If the size of a flexure is increased, then the payload capacity increases, but the tensile strength only increases by approximately a power of two, reducing the ability to absorb impact loads
Solution Approach 1:
The patent changes the material parameter from conventional steel to superelastic shape-memory alloys, which possess unique stress-strain characteristics. These materials can undergo large elastic deformations (up to 8-10% strain) before returning to their original shape, providing superior impact load absorption capacity that scales differently than traditional materials, thereby maintaining adequate tensile strength even as payload capacity increases.
Solution Approach 2:
The invention exploits the phase transition characteristics of shape-memory alloys between martensite and austenite phases. During impact loading, the material can transform phases to absorb energy through reversible structural changes at the crystal level, enabling the flexure to withstand impact loads that would exceed the tensile strength limits of conventional materials scaled to the same size.
3Strength
If conventional steel flexures are used, then the structure provides high translational stiffness, but it fails frequently under high impact loads due to insufficient rotational flexibility and shock absorption
Solution Approach 1:
The patent changes the material parameters from conventional steel to superelastic shape-memory alloys, fundamentally altering the flexure's mechanical response characteristics. This material substitution enables the structure to simultaneously achieve high translational stiffness for payload support and low rotational stiffness for vibration isolation, while the superelastic properties provide shock absorption capacity that prevents failure under impact loads.
Solution Approach 2:
The invention converts the previously harmful characteristic of high rotational stiffness into a beneficial property by using shape-memory alloys to achieve low rotational stiffness. The material's superelasticity transforms what would be rigid, failure-prone connections into flexible, shock-absorbing elements that dissipate impact energy, turning the potential harm of impact loads into a beneficial energy absorption mechanism.
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 superelastic shape-memory alloy flexures offer enhanced rotational isolation and impact absorption, reducing the likelihood of failure under high loads and allowing for larger, more effective payload isolation systems with improved energy absorption capabilities compared to traditional high-strength steel flexures.
Implementation Method 1
The plurality of radial supports can be made of a superelastic shape-memory alloy, such as Nitinol
Implementation Method 2
The use of superelastic shape-memory alloys, such as Nitinol, in the radial supports of the multi-axis payload isolation device provides improved rotational flexibility and shock absorption
Data Source
AI summary
A multi-axis payload isolation device for isolating a payload from outside motions. The multi-axis payload isolation device includes a payload mount base, a housing, and a flexure. The payload mount base is configured to support a payload. The housing includes an interior cavity for receiving and supporting the payload mount base. The flexure includes a plurality of radial supports and a common hub. The plurality of radial supports attach the payload mount base to the housing and are made of a superelastic shape-memory alloy. The common hub is configured to connect each of the plurality of radial supports to the payload mount base.