ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
45.5 N/m with an initial length of 3.2 cm was selected for the prototype unit. A spring force vector that  bisects the membrane and lanyard vectors minimized the required minimum tape spring radii. The resulting boom tape spring length was 41.3 cm and is subjected to a compressive load of 0.52 N. The  frame tape spring is 55.5 cm in length with a compressive load of 0.27 N. When sizing the tape spring to resist the compressive loading, the tape spring cross-section was  assumed to have a constant radius with a subtended angle of  /g69=/g83radians. A half-sine wave shape  imperfection with peak amplitude assumed to be 5% of the member length was used to calculate the total load in the member. The minimum tape spring radius was then determined such that the total load in the tape spring was one third of the Euler buckling load. Solving for the top frame and boom cases resulted in  the same required minimum tape spring radius of 0.38 cm. However, strain limitations for the layup limit the radius to be greater than 0.48 cm.   The tape spring should have sufficient torque to fully deploy quasi-statically, i.e., not relying on the kinetic  energy of the system to assist in the process. A torque margin of 3 was used to calculate the minimum required tape spring cross-section radius to overcome the resistive moment resulting from the axial  compressive load in the member. To account for long-term creep effects, the shear modulus in the outer  plain weave layers was assumed to be effectively zero. For a constant cross section with  /g69=/g83radians, the minimum radius is 0.41 cm. The trimmed tape spring shown in Figure 5b) has an effective subtended  angle of /g69= 0.86 radian at the root. The resulting minimum radius was 0.54 cm. This was rounded up to a  standard mandrel size 0.56 cm (7/16 in) for manufacturing purposes. A finite element model of the tape spring was created to compare the deployment torque and buckling.  Abaqus/Standard was used to perform buckling analyses to compare the buckling loads of the trimmed tape spring geometry to the pristine member. Various trials were performed with initial shape imperfections applied. The trimmed geometry was observed to have a consistent 4% reduction in buckling load capability. A buckling analysis using was then performed by continuously increasing the tension in the compliant member that connects the membrane corner point to the corner of the top triangular frame. The system buckles at an applied load of approximately 48 N, which is two orders of magnitude above the design load of 0.9 N. Figure 11.  Top frame corner free body diagram. The central disk radius of 8.5 mm was selected for the hub assembly. The moment generated from the  0.52-N compressive load in the boom tape spring required a deployment torque of at least 4.4 mN-m. The  estimated deployment torque from Equation 2 at this radius and taking into account the cross section at  506
Figure 12. Fabricated structure in the deployed and stowed configurations. Figure 13. Captured sequence from deployment test In order to verify the deployable telescope satisfies the structural requirements for an operational system,  tests such as deployment repeatability, deployed dimensional stability, and dynamic vibration are needed.  Observations from handling and testing of the prototype structure presented a number of departures from  a conceived operational unit. The combination of these factors justified reserving the characterization testing for the next structure revision that incorporates the identified design features. Conclusions The structure presented in this work incorporated flexible composite tape springs in a novel manner to  produce a relatively simple and mass efficient solution for a three-dimensional, self-deployable structure. Through the development process a number of mechanism design requirements were discovered to enable the desired functionality. The tape spring-hub interface design was a driving factor in the overall  system design and available torque factor of safety. A hub design that accommodated an untrimmed tape  spring did not satisfy the structure volume constraints. Calculations supported the trimmed tape spring end would provide sufficient deployment torque with margin. Gravitational and other parasitic loads  508
originally unaccounted for, required gravity offload support for ground deployment testing. The off-nominal  and inertial loading imparted by the passive offload system yields added uncertainty to the observed structure kinematics. Microgravity testing, or at a minimum active gravity offload support, is suggested for this class of freely deployable structure. The tape springs can be designed to deploy with no gravity offloading, but at the expense of an overly designed system that increases the deployment rate and imparted shock. Rate control has been a critical design factor in deployable structures. As mentioned previously, a viable  rate control solution for this scale of deployable structure is not available. Known methods either add excessive mass and complexity or excessively increase deployment failure risk. The relatively low mass  of the deploying structure is a small fraction of a notional 3U CubeSat spacecraft. Free deployment  testing of the SIMPLE boom (work not yet published) qualitatively had little impact on bus dynamics. The  shock loading on the membrane optic in this application is of larger concern. The test data required per Reference 11 to more accurately predict the deployment torque was not  available for the selected laminate. AFRL Space Vehicles directorate is currently constructing a database  of commonly used lamina and laminates to provide this data for future efforts. A test to directly measure  the operational tape spring torque over the full deployment would also be beneficial to verify the calculations. Successful deployment tests were observed to be highly sensitive to simultaneous release of the tape spring rotation constraints. Preliminary functional testing during the design development phase revealed  deployment failures often resulted when one top frame hub was released before the other two. Because  the top frame deployment does not work against gravity, the rapid motion of the top frame corner fixture would cause the boom tape spring to deploy in a lateral, rather than vertical, fashion that resulted in gross  lateral shifting of the top frame assembly. The final hub constraint mechanism using the locking/unlocking  slip disk allowed all tape spring rolls to be consistently stowed in a more deterministic fashion against the  hard stops and tightly wound about the central hub disk. Proper packaging in this manner was found to be critical for synchronous deployment. The resulting hub and constraint mechanism design enabled  repeatable functional three-dimensional deployments. The deployment tests successfully demonstrate  that flexible composite tape spring members can be utilized to enable simple and efficient deployable  structures. Acknowledgments This work was financially supported by Integrated Design, Analysis, and Testing Of Space Structures  (IDATS) [Contract #FA9453-11-C-0265] Program Manager: Andrew Williams, and executed at the Air  Force Research Laboratory Space Vehicles Directorate, Kirtland AFB 87117. The authors would also like  to thank Michael Peterson for his contribution in solid modeling tasks and Daniel Roldan for assisting in  hardware assembly and deployment testing. 509
References 1. Mejia-Ariza, J. M., Murphey, T. W., and Dumm, H. P., “Deployable Trusses Based on Large  Rotation Flexure Hinges,” Journal of Spacecraft and Rockets, Vol. 47, 2010, pp. 1053–1062. 2. Murphey, T. W., Jeon, S. K., Biskner, A., and Sanford, G., “Deployable Booms and Antennas  Using Bi-stable Tape- springs,” 24th Annual AIAA/USU Conference on Small Satellites, 2010.  3. Pollard, E., Murphey, T. W., and Sanford, G. E., “Experimental and Numerical Analysis of a  DECSMAR Structure’s Deployment and Deployed Performance,” 48th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2007.  4. Jeon, S. K. and Murphey, T. W., “Design and analysis of a meter-class CubeSat boom with a  motor-less deployment by bi-stable tape springs,” 52nd AIAA/ASME/ASCE/AHS/ASC Structures,  Structural Dynamics, and Materials Conference, April 2011.  5. Rimrott, F. P. J. and Fritzsche, G., “Fundamentals of STEM Mechanics,” IUTAM-IASS  Symposium on Deployable Structures, Theory and Applications, Sep 06-09, 1998. 6. Footdale, J. N. and Murphey, T. W., “Structural Design of a CubeSat-Based Diffractive Optic  Telescope,” 52nd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2011. 7. Footdale, J. N. and Murphey, T. W., “Design and Testing of Self-Deploying Membrane Optic  Support Structure Using Rollable Composite Tape Springs,” Proceedings of the 54 thAIAA  Structures, Structural Dynamics, and Materials Conference, Boston, MA, 2013. 8. Seffen, K. A. and Pellegrino S. “Deployment Dynamics of Tape Springs,” Proceedings of the Royal Society London Series A, Vol. 455, pp 1003-1048, 1999.  9. Pellegrino, S., “Bi-Stable Structures,” /g39/g72/g83/g79/g82/g92/g68/g69/g79/g72/g3/g54/g87/g85/g88/g70/g87/g88/g85/g72/g86 , SpringerWien, New York, 2001, pp.  99-111.   10. Pollard, E. L., and Murphey, T. W., “Development of Deployable Elastic Composite Shape  Memory Alloy Reinforced (DECSMAR) Structures,” 47th AIAA/ASME/ASCE/AHS/ASC  Structures, Structural Dynamics, and Materials Conference, Newport, RI: AIAA, 2006. 11. Peterson, M. E. and Murphey, T. W. “Large Deformation Bending of Thin Composite Tape Spring  Laminates,” 54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials  Conference, Boston, MA, 2013.  12. Murphey, T. W. and Peterson, M. E., “Four Point Bending of Thin Unidirectional Composite  Laminas,” 54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials  Conference, Boston, MA, 2013. 13. Domber, J. L., Hinkle, J. D., Peterson, L. D., and Warren, P. A., “Dimensional Repeatability of an  Elastically Folded Composite Hinge for Deployed Spacecraft Optics,” Journal of Spacecraft and Rockets, Vol. 39, No. 5, pp. 646-652, 2002. 14. Kwok, K. and Pellegrino, S., “Folding, Stowage, and Deployment of Viscoelastic Tape Springs,”  AIAA Journal, Vol. 51, No. 8, 2013, pp. 1908-1918. 15. Hyer, M. W., Stress Analysis of Fiber-Reinforced Composite Materials, WCB/McGraw-Hill, 1998. 510
Figure 1. (Left) 2 x 2 m, 40-MHz Ra bber antenna, three times successfully launched by Indian  rocket, (Middle) MUPUS Deployment Device for Rosetta mission, (Right) laboratory  model of Ultra-Light Planetary Manipulator (ULPM) – 3-dof, 3-m operational range, mass  of 2.5 kg. All the above-presented devices used Ø15-mm or Ø25-mm tubular booms of stainless steel strips  produced in Ukraine. Recently, the CBK PAN activities were concentrated on application of a miniature  Ø6-mm tubular boom made of beryllium bronze, more compact and lighter than the stainless steel ones (it  weighs 8 g per 1 m, while the previous booms weigh 50 g and 100 g per 1 m respectively). The original  manufacturing method developed by the Polish enterprise GUTRONIC, a longtime CBK PAN partner, will be described later in the paper. The demand for such an ultra-light and scaled-down solution arose from the Russian RELEC mission. Within the framework of that mission, CBK PAN developed the Radio Frequency Analyser (RFA) – an instrument devoted to measure three electrical components of radio frequency emissions in the frequency range from 50.0 kHz up to 18.0 MHz. One of the main units of RFA was a three dimensional electric  antenna set shown in Figure 2.  Figure 2. RFA – set of three orthogonal 1 m long antennas for RELEC mission. As mentioned above, the RFA antenna set is based on miniature Ø6-mm tubular booms stored on a reel.  In principle, the tubular boom is to extend itself by spring energy, which is released during transformation  of the input flat profile to the original round one. The storage reel is on the front and performs rotational and translational motion. The reel is attached to the tubular boom to never become space debris after deployment. This solution, despite intrinsic advantages like design simplicity and lack of a motor drive, cannot be recommended as the perfect one, for three reasons: 512
/g120 The deployment process is characterized by high and uncontrolled speed. This can be against  certain mission constraints, especially in small satellites threatened with stability loss in case of rapid  and dynamic actions.  /g120As a baseline, a reel is separated from the boom at the end of deployment and becomes space  debris. A design allowing keeping the reel at the antenna end, like in RFA, is applied, however, from  the electrical point of view, it is an unfavourable solution.  /g120The tubular boom acts as a driving spring. In case of spring relaxation (e.g. as a result of a long flight  to a destination) or an unexpected boom jam, there is no deployment salvage. MAB Background Bearing in mind the aforesaid disadvantages of free deployment with the leading reel, CBK PAN  undertook a task to create an alternative solution with significant improvements. Roughly at the same  time CBK PAN was allowed to place additional payload instruments on board BRITE-PL Heweliuszsatellite. In this way, MAB was proposed as a prototype of the tubular boom antenna driven by the modified escapement mechanism. MAB is a technology demonstrator aimed only at showing correctness  of the novel deployment mechanism idea without testing the antenna performance itself (i.e., reception  characteristics, antenna response and sensitivity). The fully functional prototype developed for the BRITEtype spacecraft is presented in Figure 3. Figure 3. MAB – technology demonstrator for BRIT E-PL Heweliusz satellite:  (left) stowed, (right)  partially deployed configuration.  In general, the tubular boom strip made of beryllium bronze (like the one used in MAB) can be stored on a  reel and when deployed, it can form a 1.5-m long cylindrical tube. However, for safety reasons, in case of  antenna deployment failure, the tube on BRITE mission is only 120-mm long and deployed inside a cylindrical casing (Figure 4). A closing contact placed at the free end of the safety casing verifies and  confirms the antenna deployment.  The device passed qualification tests, described in detail hereinafter, achieving therefore TRL 6, and is  ready for launch. BRITE-PL Heweliusz was to be launched in December 2013 on board the Chinese CZ4B rocket. Unfortunately, due to the failure of the preceding flight of the same rocket type, the launch was  postponed. The Chinese investigation is still ongoing and, according to recent update, the satellite will be probably launched in February 2014. Following the performance in a space environment, MAB is  expected to gain TRL 7. 513
Figure 4.  Flight model: 1 – MAB, 2 – safety casing, 3 – closing contact, 4 – bracket. Technical Features of the New Deployment Mechanism The idea of the new deployment mechanism applied in MAB originates from an escapement – a device  commonly used in mechanical watches and clocks. Traditional clock escapement A perfect example to show the principle of operation of a traditional escapement mechanism is a gravity  clock (Figure 5). The escapement is driven by force from a suspended weight (1) while a pendulum (2)  acts as a timekeeping element. An escape wheel (3) works with a detent (4). The detent releases a tooth  of the wheel, which therefore changes from a locked state to a drive one until the opposite detent arm strikes another tooth on the gear, which locks the gear again. Such a mechanism, with meticulously  selected pendulum properties, allows clocks to precisely indicate the passage of time. A characteristic clock ticking is nothing but the sound of the gear stopping when the escapement locks.  Figure 5.  Gravity clock escapement mechanism:  1 – weight, 2 – pendulum, 3 – escape wheel, 4 – detent. 1 3 4 213 42 514 1111 33333 4444 22
Initially, the traditional Graham escapement (an escapement type used in almost all modern pendulum  clocks) was developed in MAB that constituted the antenna solution with the reel joined to the spacecraft and the escape wheel fixed to the reel shaft. The tubular boom, stored on the reel, performed a function  of a weight and thus a driving force. A pendulum was replaced with an electromagnet. In that way MAB  was provided with a very precise speed regulation dependent only on the electromagnet timing rate. One  of the main RFA disadvantages – high and uncontrolled deployment speed – was eliminated. However,  the solution was still not free of consequences of the driving spring relaxation or accidental boom jam. Innovative escapement-based mechanism The modified escapement mechanism proposed by CBK PAN turned out to be an innovative solution free  and clear of any RFA defects. The geometry of the detent and escape wheel underwent a significant  change aimed at the breaking properties decrease corresponding with efficiency improvement and higher deployment reliability. The main modification was that the escapement lost its self-locking attribute.  The schematic of MAB deployment mechanism is shown in Figure 6. The tubular boom (1) is rolled up on  the reel coupled with the escape wheel (2). The wheel works with the detent (3) fixed to the armature (4) which is driven by the electromagnet (5) and return spring (6). Once released, tubular boom starts free  unwinding. The detent, sliding on the escape wheel teeth, is forced to perform swinging motion. The deployment speed is regulated via eigenfrequency of the detent mechanism. No electromagnet action is  required. In case of a much lower than desired deployment speed or unexpected boom jam, the escapementbased mechanism serves as a motion-inducing unit. With the use of electromagnet and return spring the detent swinging movement is forced, the escape wheel begins to rotate and thereby aiding the unreeling action. Moreover, the electromagnet working at high frequencies can act as a generator of vibration, also  valuable in providing better unwinding (confirmed by tests).    Figure 6. Modified escapement mechanism for MAB depl oyment: (left) isometric view, (right) side  view; 1 – tubular boom stored on the reel, 2 – escape wheel, 3 – detent, 4 – armature, 5 – electromagnet, 6 – return spring   The only inconvenience of the proposed mechanism is the limited speed control. The deployment rate, although satisfactorily mitigated and slowed down, depends closely on the detent mechanism inertia. The inertia properties of the detent subassembly strictly determine the deployment speed. The pictures in  Figure 7 present two versions of MAB:  initial (with the traditional Graham escapement) and the final one  515
(with the modified escapement). CBK PAN has made an effort to obtain a patent for the invention  described in this paper since the special escapement mechanism has a potential to be reused in other devices in the future. The property rights registration process commenced in October 2013 (Polish Patent  Office no. P.405646).  Figure 7.  Comparison of MAB versions: (left) with Graham escapement, (right) with modified one. MAB basic characteristics MAB is a prototype of the antenna equipped with: the innovative escapement drive acting simultaneously  as a speed damper and a new type of a miniature tubular boom – these are paramount distinguishing  MAB features. A non-explosive lock & release mechanism is also noteworthy (Figure 8). It is based on the  Dyneema string melting system (with the use of a resistor as a heater), which was space proven in several CBK PAN previous instruments [4]. This kind of actuator is very reliable, especially at low  temperature applications. The Dyneema string continuous tension is realized by an extra kick-off spring  that also supports the release action. The MAB operation is fully controlled by an external control board. Once initiated, the deployment system  receives a deployment command – the resistor is heated up for 10 s, which makes the Dyneema  filaments melt. The released tubular boom starts free unwinding at moderated speed until leaning against  the closing contact. Then a signal is sent that stops the operation. In case of the boom jam (and hence the lack of the stop signal after 10 s), the electromagnet serving as  an extra motion-inducing unit is powered and thereby the unreeling action takes place. The procedure is stopped either via the stop signal sent from the closing contact or after 120 s. In the latter case (or in any  when the unplugging signal is not sent), the deployment would be considered as unsuccessful. The main MAB characteristic features: /g120miniature size and low weight: 30 x 40 x 50 mm, 35 g, /g120smooth and regular deployment without rapid and dynamic actions (no risk of satellite stability  loss), deployment speed – 10 cm/s, /g120usage of no electrical motors resulting in a simpler construction and higher reliability – the  electromagnet individually optimized to the specific requirements must be a more reliable and  higher-class solution than a common motor, especially the one with a reduction gearbox, where  the number of moving parts and frictional joints is significant, /g120advantageous length to weight ratio (120-mm-long boom weighs less than 1 g),  /g120relatively low power consumption: 4 W for 10 s (for lock & release mechanism), 1.25 W for 30 s  (for electromagnet, if needed to be used), /g120once deployed, the antenna cannot be retracted. 516
Figure 8. Lock & release mechanism used in MAB: 1 – Dyneema string, 2 – heater, 3 – kick-off  spring Technical Features of the New Manufacturing Technology Another challenging and innovative issue is the manufacture of the new kind of miniature tubular booms   (6 mm in diameter). The manufacturing process requires several factors to be taken into account: low thickness of the boom, its fragility, tendency to torsional/bending deformations, and geometry degradation  arising from multitude of manufacturing effects such us heterogeneous material properties, uneven heat  treatment, and aging of material. A careful control of dimensional tolerances during production of the  boom may be crucial for a successful mission [5]. Therefore, the chosen production method must ensure  as precise manufacturing of tubes – free of any material defects – as possible.  Analyses showed that none of the reviewed existing methods of open profile metal tubes manufacturing  fits completely to such a specific task as production of thin-walled tubular booms. The innovative method  for producing beryllium bronze tubular boom – 0.05-mm thick, 1.5-m long and 6 mm in diameter – has been developed by the Polish enterprise GUTRONIC during the ESA PECS 4000105010/11/NL/KML project. That innovative method, undeniably unique in Europe, has been a subject of a patent since April 2013 (Polish Patent Office no. P.403660). The employed method of tubular booms manufacturing is  presented in Figures 9 and 10 in a simplified form. The scheme is shown in Figure 9. The tape (1) is placed on a susceptible tie (2) travelling in a prismatic base (3). The tie is clamped to the  prism by a forming rod (4) being a part of the pressure providing unit. A beryllium tape being formed  travels on a tie and is inserted under a forming rod and thereby into the working area (5). The rod rolls on the tape making it bend. The working area is determined by radiuses of the rod cross-section, perpendicular to the prism surface. 2  1 3 517