SHEAth-based Rollable LEnticular-Shaped and Low-Stiction (SHEARLESS) Composite Booms
mechanical and fluid systems
SHEAth-based Rollable LEnticular-Shaped and Low-Stiction (SHEARLESS) Composite Booms (LAR-TOPS-268)
Lightweight support framework for deployable structures that can be stowed compactly
Overview
NASA's Langley Research Center has developed the SHEARLESS composite boom with a final cross-section shape that is lenticular and is flexible enough to allow elastic flattening and subsequent coiling around a cylindrical reel / drum. The torsional stiffness of the structure is also greatly increased and becomes two orders of magnitude larger than that of the individual tape-spring components alone. The innovation enables a lightweight structure that can be stowed on a reel without appreciable shear stresses developing in its constitutive composite parts. This allows for unprecedentedly small coiling diameters for the total thickness of the structure, which can enable highly compact designs such as those required in CubeSat/small satellite applications.
The Technology
The SHEARLESS composite boom has a rollable structure with a large moment of inertia per unit of stored height that does not suffer from shear-derived problems. The boom is fabricated from joining two independent tape-springs front-to-front with the use of a durable seamless polymer sleeve. This sleeve allows the two parts to slide past each other during the coiling/deployment process so as to minimize shear and its derived problems. The innovation enables a lightweight structure that can be stowed on a reel without appreciable shear stresses developing in its constitutive composite parts, allowing for unprecedentedly small coiling diameters for the total thickness of the structure. As demonstrated, through specific laminate design of the two inner composite parts, the SHEARLESS composite boom can also be fabricated with a special inherent feature, bi-stability, which enables designs with minimal mechanisms and aids in deployment controllability and reliability.


Benefits
- Enables a lightweight structure that can be stowed compactly
- Good performance for torsional stiffness of the structure
- Inexpensive to fabricate
Applications
- Deployable space structures (solar panels, antennas, etc.)
- Deployable terrestrial structures (emergency shelters, clean rooms, etc.)
- Backpack solar collectors
- Inspection booms (down-pipe cameras, hazardous environments, etc.)
Similar Results

Deployable Composite Boom
Just like a kid's slap bracelet, the Bi-CTM design includes a secondary stable low-energy state aside from the rigid deployed state. The result is that the Bi-CTM is not under high-spring stress when coiled up which simplifies the stowage process as well as enabling a more controllable extension of the boom. The simplified stowage process enables reduced size, mass and complexity of the storage and deployment mechanism system.
Compared to the majority of deployable thin-shell booms, which have at best a semi-open cross section, this true closed-cross-section boom is stronger, while keeping the compact nature of rollable booms, and is able to overcome both bend and twist buckling related limitations.
Using omega-shaped cross sections with optionally circular, parabolic or ellipsoidal segments, where each half of these thin-shell composite booms can use equal (symmetric boom) or different (asymmetric boom) cross section geometry and/or composite laminates, offers a great deal of boom customization in terms of stable coiled diameter and structural properties.
Bi-CTM boom design optimization provides for maximized area moments of inertia and torsional constant, which related to the boom stiffness and the loading capacity, while remaining a bistable design.

Composite Joint Connector
This technology is a joint connector for application between two or more tubular parts, or to connect one or more tubular parts to a fixed structure. This attachment technology is more structurally efficient and reduces failure characteristics due to the uniformity of composite material across the joint. In comparison to a typical joint, this technology reduces weight while minimizing stress variations that lead to structural failure. Moreover, typical joints must be bonded or screwed together, which further reduces efficiency. The invented technology, however, is designed so that it is both bonded and mechanically locked by design rather than relying on separate mechanical fasteners. The result is a design that mitigates failure of a structural joint.

Handheld Metal Tube Straightener
NASAs Handheld Metal Tube Straightener is built with a stationary anvil and a dynamic hammer attached to a knob/lead screw. The extension and retraction of the hammer is manually operated by the knob. The tube straightener contains an oval opening that serves as an insertion point for the to-be-straightened tube. Once the tube is inserted, the hammer can be repetitively clamped and unclamped while progressively inserting the tube until it passes through the tools built-in "GO" gauge, which is a tolerance inspection device. After the tube passes through the GO gauge it appears in a GO window indicating that the proper length of tube has been straightened. The operation of the tube straightener results in the straightening of a tubes first 3.5 inches, including the tip, so that it can be swaged into any commercial swage fitting.
NASAs Handheld Metal Tube Straightener has a technology readiness level (TRL) 9 (actual system flight proven through successful mission operations) and the related patent is now available to license. Please note that NASA does not manufacture products itself for commercial sale.

Cord Tension Measurement Device (C-Gauge)
The C-Gauge is made of a 3D-printed aluminum body with strain gauges attached to the inner and outer walls of the connecting beam. The legs of the gauge attach firmly to the cord. When the cord is stretched, the tension in the cord goes through the legs and into the beam, causing it to bend. This bending creates a tension and compression stress in the bottom and top surface of the beam, respectively. The strain gauges capture the tension and compression, which are then used to determine the tension in the cord. The use of multiple strain gauges mitigates any torsion loading of the gauge and provides a direct measurement of the axial tension load of the cord.
The C-Gauge is a low-profile, non-invasive system that can be installed onto an existing cord in a system (e.g., the suspension, reefing, or riser lines in a parachute) without the need to remove or re-install the cord. It is small and lightweight and does not add stiffness or weight to the cord and thus does not affect the dynamics of the parachute or the structural response of the system. The C-Gauge can be scaled to larger and smaller sizes to measure larger and smaller load capabilities, dependent on the cord.
The C-Gauge is at a TRL 4 (component and/or breadboard validation in a laboratory environment) and it is now available for your company to license and develop into a commercial product. Please note that NASA does not manufacture products itself for commercial sale.

Continuous Fiber Composite for Use in Gears
Designers are constantly seeking to improve the power-to-weight ratio of components in rotorcraft and other flight vehicles. One approach has involved using lightweight carbon fiber composite materials to replace gear web portions and other components that are typically made from steel. The problem with using fiber composite materials comes when more complex shapes are required. To create thickness variation and other accommodations for complex shapes, manufacturers can stack cut continuous fiber plies and/or form short, fiber-reinforced composite material to the desired shape. Unfortunately, these methods leave cut fiber ends within the structure, which often become initial sites for high cycle fatigue damage in high speed, high power density applications. Glenn's new method tackles this problem with one of three approaches. The first approach is applicable to gears that are planar in shape and have a single hub and a single rim. The hub and web sections of the gear are made as an integrated structure with decreased thickness from the hub inner diameter to the web outer diameter. The thickness variation is accomplished using multiple layers of continuous fiber composite material formed to specific shapes and separated by filler materials. The second approach is applicable to gears that have an extended gear body in the axial direction rather than a simple planar structure. In this approach, the gear body is made using multiple layers of continuous fiber composite material in the shape of a solid of revolution. The third approach is a power transfer assembly made by combining approaches one and two. With any of these three approaches, the material can be tailored to the structure by the properties of fibers used, the number of fiber layers used, and the location of the fibers relative to the neutral axis of the structure. Glenn's innovation opens the door for carbon fiber composite materials to be used for many applications for which they were previously unsuited.