Tape-Spring Hinge with Shape Memory Alloy for Compact Deployment
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Solution Overview
Problem
Deployable structures face a challenge in minimizing the folded radius while maintaining stiffness and strength, as increasing cross-section thickness for improved performance results in larger stowed volumes and increased mass.
Innovation Solution
A non-axially prismatic, thin-walled tape-spring shaped element with strategically placed resilient, compliant hinge regions and rigid non-hinge regions, incorporating shape memory alloy features for enhanced stiffness and controlled strain release, achieves a smaller packed volume and reduced mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cross-section thickness of the tape spring is increased to improve stiffness and strength, then the structural performance is improved, but the folded radius and stowed volume increase
Solution Approach 1:
The tape spring is segmented into distinct hinge regions with reduced thickness for folding and rigid non-hinge regions with increased thickness for structural strength. This segmentation allows the structure to achieve both small folded radius (through thin hinge regions) and high stiffness (through thick rigid regions), resolving the contradiction between strength and stowed volume.
Solution Approach 2:
Different cross-section thicknesses are applied to different locations of the tape spring based on functional requirements. The hinge regions have reduced thickness to enable tight folding, while the rigid regions have increased thickness to provide structural strength. This local differentiation resolves the contradiction by optimizing each region's thickness for its specific function rather than using uniform thickness throughout.
2Strength
If the cross-section thickness is increased to maintain structural stiffness during deployment, then the deployed structure performs better, but the mass of the structure increases
Solution Approach 1:
The tape spring structure is divided into hinge regions and rigid regions with different thicknesses. The hinge regions use thinner material to reduce mass while still providing necessary flexibility, and the rigid regions use thicker material to ensure structural stiffness during deployment. This segmentation resolves the contradiction between mass and structural stiffness by applying material efficiently only where needed.
Solution Approach 2:
The cross-section thickness is locally optimized: thinner in hinge regions where flexibility is prioritized and thicker in rigid regions where stiffness is prioritized. This local quality approach reduces overall mass compared to a uniformly thick structure while maintaining the required structural stiffness in critical areas, resolving the contradiction between mass and stiffness.
3Ease of operation
If a uniform resilient continuum is used throughout the articulating member to enable folding, then the structure achieves compliance, but the mass and stowed volume increase
Solution Approach 1:
The articulating member is segmented into compliant hinge regions and rigid non-hinge regions. Only the hinge regions use resilient, compliant material to enable folding, while the rigid regions use stiffer material for structural support. This segmentation reduces overall mass compared to a uniformly compliant structure while maintaining the necessary folding capability in critical areas.
Solution Approach 2:
Different material properties are applied locally: resilient and compliant material is used only in the hinge regions where folding is required, while rigid material is used in the non-hinge regions for structural support. This local differentiation achieves the necessary compliance for folding without the penalty of increased mass that would result from using compliant material throughout the entire structure.
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
This configuration allows for a minimal folded radius with maintained structural performance, achieving greater mass efficiency and efficient packaging, while the integrated shape memory alloy ensures controlled deployment and strain sequencing.
Implementation Method 1
Shape memory alloy features are integrated into the hinge region to serve as folding mandrels
Implementation Method 2
tape-spring shaped element with an embedded hinge... has strain energy capacity, which when released, can motivate the reconfiguration of the structural system
Implementation Method 3
When released they spring back to their strain free shape and have a tendency to lock into this lower energy state
Data Source
AI summary
A tape-spring shaped, articulating member used in deployable structures having a resilient, compliant hinge region and rigid non-hinge regions, thereby enabling a smaller fold radius and greater packaging efficiency. The increased compliance in the hinge region may be obtained by using a more compliant material in the hinge region or reducing the cross-sectional area in the hinge region. The hinge region may be reinforced with integrated shape memory alloy features serving as folding mandrels, to enhance structural stiffness and strength performance of the hinge, and to exhibit authority over the rate and sequencing of strain release when deployed.