Triangular Rollable Collapsible Boom Bending Stiffness
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Solution Overview
Problem
Existing spacecraft deployable booms face challenges in achieving a balance between structural depth, material thickness, and packaged height, with previous designs requiring large strains to furl and resulting in either tall packaged heights or reduced material thickness, limiting their bending stiffness.
Innovation Solution
The Triangular Rollable and Collapsible (TRAC) boom design features two curved flanges attached at their upper portions to form an open triangular cross-section, allowing for a larger cross-section inertia to packaged height ratio and using thicker materials, while maintaining sufficient torsional stiffness, with a flange radius and flare angle optimized for maximum bending stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the boom uses a circular cross-section configuration (STEM), then it is simple to fabricate and package, but it results in a tall packaged height relative to the deployed boom diameter
Solution Approach 1:
The invention transitions from a circular cross-section to a triangular cross-section configuration. This dimensional change in the cross-sectional geometry allows the boom to achieve a more favorable packaged height to deployed diameter ratio, reducing the packaged height by approximately 40% compared to circular configurations while maintaining structural performance
2Length of stationary object
If the boom uses a lenticular configuration (CTM), then it has half the packaged height as the STEM, but it requires symmetric bell shaped halves bonded at edges increasing complexity
Solution Approach 1:
The triangular cross-section boom is segmented into two curved flanges that are attached at their upper portions. This segmentation allows the boom to achieve the reduced packaged height of lenticular designs while using a simpler attachment method at the ridge, avoiding the need for complex bonding of symmetric bell-shaped halves
Solution Approach 2:
The invention employs an asymmetric triangular cross-section with two curved flanges of potentially different geometries, allowing optimization of each flange's curvature radius independently. This asymmetric configuration enables reduced packaged height while maintaining structural integrity through optimized stress distribution
3Length of stationary object
If the boom uses thinner materials to reduce packaged height, then it achieves shorter packaged height, but it reduces the bending stiffness
Solution Approach 1:
By changing the cross-sectional geometry from circular to triangular, the invention increases the cross-sectional inertia for a given material thickness. This dimensional change in geometry allows the use of thicker materials in the triangular configuration, thereby increasing bending stiffness while maintaining the reduced packaged height advantage
4Strength
If the boom increases structural depth to increase bending stiffness, then it achieves greater bending stiffness, but it increases the packaged height
Solution Approach 1:
The triangular cross-section geometry provides a more efficient distribution of material away from the neutral axis compared to circular configurations. This dimensional change in cross-sectional shape increases the cross-sectional inertia, allowing greater bending stiffness to be achieved for the same packaged height, or equivalently, reduced packaged height for the same bending stiffness requirement
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 TRAC boom achieves 10 times greater bending stiffness than a lenticular boom and 34 times greater than a Storable Tubular Extendable Member (STEM) boom with the same packaged height and material, while reducing the strain required for flattening, enabling a stiffer and more efficient deployable structure.
Implementation Method 1
a boom structure composed of a resilient material that is elastically deployable from a flattened configuration
Data Source
AI summary
An elastic space-deployable boom of carbon fiber reinforced plastic or other resilient material having an open substantially triangular cross-section when deployed and stowed with a flattened cross-section about a circular hub.