– Gold Sponsor Showcase –
High Strain Composite Boom Deployer Design
Through Iterative Test and Hardware Rich Development
Brad Hensley, Roccor LLC
Tayler Thomas, Roccor LLC
2602 Clover Basin Dr., Suite D.
Longmont, Colorado 80503
Roccor is an industry leader in the development and implementation of high strain composite materials in spacecraft deployable systems. Metallic strained deployables have been used in space for over 50 years; a common example is a slit tube, or “tape measure”, boom. These mechanisms coil a long “C” cross-section boom around a spool and then deploy the boom on-orbit, providing a high packaging efficiency and the ability to deploy to various lengths. Metallic slit tubes booms can have many advantages over other deployable structures (telescoping booms, hinged booms, etc.) but are limited in their structural performance and are susceptible to large thermal deformations.
Roccor is expanding slit tube boom technology by using High Strain Composite (HSC) materials as the rollable structural element. The nature of the composite laminate enables a neutrally stable system that, unlike metallic slit tubes, does not require a complex set of root mechanisms to restrain the stored energy of the coil. These laminates, consisting of space qualified materials, can also be designed to have a near zero coefficient of thermal expansion, eliminating thermal deformations. Roccor has also developed the capability to embed conductors into the boom, which can then act as an RF element or transfer power and data without a standalone harness.
Using these technologies Roccor has developed a high strength, high precision Cubesat boom for use in tensioned structures. This system is designed for use in complex precision structures, such as deployable antennas, optical systems, and solar arrays. The key performance parameters of this system are a deployed axial precision of .1 mm and a deployed compressive strength of 225 N. HSC’s allowed Roccor to develop a system with higher performance than comparable deployables in terms buckling strength, dimensional stability, and mechanism simplicity. One key to utilizing HSC structures is the clear understanding of the physical shape of the deformed material. The strains within the laminate are directly tied to the long duration performance of the material and hence are important to characterize to a high level of certainty. In addition, residual stresses within the laminate can cause the material to creep over time, causing changes to the deployed shape long after the deployment is complete. Roccor has developed several processes to combat these issues utilizing contact free measurement techniques enabled by a Portable Coordinate Measurement Machine (PCMM). Roccor also ran into several issues during the design development, most notably composite damage during repeated deployments, that were solved through the techniques developed using the PCMM and a hardware rich development process. This talk will present Roccor’s design and risk mitigation methods in detail and discuss the solutions Roccor implemented, including the testing and analysis methods Roccor developed to evaluate potential designs. Three protoflight units of this system have been delivered for flight, and further development has been ongoing on a second generation design.