ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
119 Lifetime tests  All the samples have successfully completed this test at both extreme temperatures. The values obtained  during the 100 actuation cycles at each temperature for strain, stress, resistance and times show a high stability in the actuator behavior along its lifetime at the highest and lowest temperature in the working range.   This shows that the present actuator technology is mature to be used in applications with these environment and lifetime conditions. The test has shown the material capabilities to satisfy the lifetime requirements in the current application. It should be taken into account that the samples have suffered a larger amount of cycles during the whole test campaign, so the actual lifetime obtained is >200 cycles. Figure 6(a) shows the high stability in the strain behavior along the cycles in the lifetime test at +125ºC. A comparative view for some of the cycles is shown in Figure 6(b). Future test will be conducted to verify the full capabilities of the technology in terms of lifetime. Tests will be completed in order to obtain the real lifetime limit for a 3.5% strain. Furthermore, other lifetime tests will be performed with different strain levels.      (a)                                                                        (b)  Figure 6. Results of lifetime tests: (a) Lifetime (+125ºC) – Strain (%) vs. Time (s) (b) Detailed  cycles: 1, 25, 50, 75 and 100.   Vacuum test  The cycles were successfully completed during this test. Complete actuations were achieved by using a power less than 1 W. The minimum required power to complete the actuation and the response time, are lower than the obtained in air, as could be expected. Finally, the material has not shown any problem related to the vacuum level during the test. More tests at higher vacuum levels will be done in the future in order to ensure the material works in a space environment. The main results obtained by SMARQ during the characterization test campaign in comparison to NiTi alloys are shown in Table 2.  An excellent behavior in terms of operating temperatures was shown, with capabilities to operate over the limits of current SMA technologies. Good results in terms of reliability and lifetime were also obtained during this work. Successful results were also found during the vacuum tests. Further work is being carried out in order to obtain extra information about the material, especially related to lifetime and vacuum behavior. Research work for the material resistivity optimization are on course and based on the SMARQ heritage, a new generation of mechanisms based on this technology will be developed in the near future.
120 Table 2. SMARQ Performances. 

Property Units SMARQ NiTi  Transformation Temperature (A f) °C > 150  (173°C) Max. 100  Non-actuating Temperature °C > 125  (As=152°C) Max. 80  Difference (A s - A f) °C 21 20 – 30  Thermal hysteresis °C 15 30  Max. Strain recovery  (One way memory) % ~ 8 6 – 8  Maximum Strain (Superelasticity) % > 8 8  Recovery Stress (Martensite to Austenite) MPa ~120 300 – 600  (Max)  Maximum Strength (Martensite) MPa ~500 800 – 1000  Elongation at Failure  % 12 10 – 15  Stress Rate MPa/°C 2 4 – 20  Electrical Resistivity (Martensite) 10-6 Ω ·m 0.1 0.5 – 1  Power Consumption 10-6  W·m2/m 24.2  (min @ -70ºC,  air convection)< 60  Response time s 4.5 s  (Tested geom.  @-70ºC, 4.5W,  Af=173ºC) (*) 4.3 s  (Test geom. @- 70ºC, 4.5W,  Af=90ºC)  Lifetime Cycles Tested > 100  (3.5%) (*) 100 (6%)  105 (2%)  107 (0.5%) 

(*) No complete tests were performed to establish these parameters. Partial tests were carried out as a first approach. Neverth eless,  the values are expected to be competitive with respect to NiTi. 

 Table 3. Rotary actuator main characteristics. 

Characteristic Value Notes  Mass < 9 grams without control FPGA  Power consumption 2250 mW during 0.75 ms   Voltage operation 5 V   Torque 15.75 N/mm   Rotary movement 40º   Life  >700 cycles   Operational temperature range -90 °C to +25 °C   Survival temperature range -90ºC to +70ºC   Operation time in vacuum <750 ms 750 ms correspond to the worst case.  This value depends on the initial temperature of the  actuator.
121 A Rotary Actuator for Dust Sensor 

One application of SMA based actuators is the presented, which comprises a rotary mechanism actuated by a SMA Fiber, a position sensor, an electronic driver and a control algorithm. Table 3 presents main technical details of the rotary actuator integrated in the Dust Sensor device. The actuator integrated in the Dust Sensor is an ultra-light weight rotary actuator based on a Shape Memory Alloy (SMA) fiber. The SMA fiber contracts when heated beyond the characteristic transition temperature of the material. This contraction is used for generating a rotary movement of a stick reflector. The stand-by or relaxed position is reached thanks to a return spring. The actuator has an integrated rotary position sensor for control and characterization of the actuator movement. This rotary sensor is a double capacitance detector which gives a rough position value of the reflector. The consumption of this sensor is negligible and its weight is very low since part of the sensor is integrated in the PCB of the Dust Sensor. A limit switch (end of stroke) is included as a redundant element to switch off the activation of the DS. This switch will detect that the reflector stick has reached its final position, the signal will be interpreted by the FPGA and immediately the actuator will be powered off. The actuator hardware includes an electronic driver that provides the SMA fiber a power line of +5V, ~500 mA. For reliability reasons, the driver is commanded using a signal above 1 KHz from the control FPGA, neither a 5 V DC nor 0 V DC signal will activate the SMA. A control algorithm completes the actuator system.                                                                 (a)                                               (b)  Figure 7. Initial (a) and further (b) position of the reflector stick.   The algorithm running on the Dust Sensor FPGA commands the actuation receives information of temperature, rotary position and limits switch sensors and sends a feedback to the electronic driver. Figure 7 shows the initial and further position of the stick reflector during an actuation  Qualification Campaign of Dust Sensor  Qualification objective is to demonstrate that the Dust Sensor conforms to the requirements of the mission including margins. The following tests have been applied to the Qualification Model of the Dust Sensor:   Thermal cycling and vacuum test from -90ºC to 70 ºC, 6 cycles.   Vibration. QM DS was subjected to qualification levels of sinusoidal and random vibration.   Bioburden reduction. Due to planetary protection requirements, a bioburden reduction  process shall be applied to the DS unit.   Humidity low-temperature verification test. A low-temperature verification test in a humidity  atmosphere was carried out.
122  Shock. QM of the DS was subjected to three different shock tests in each of the three axes.  Qualification levels of the test are as following:  o Axis X and Z: 500g in the form of sinusoidal half-wave with a duration of 2 ms.  o Axis Y: 2000g in the form of sinusoidal half-wave with a duration of 15-20 ms.   Test results  The following qualification tests results are presented:   Vibration. After vibration tests, a visual inspection, physic properties verification and several  functional tests were carried out with the result of no anomalies or deviations detected. Consequently, the rotary actuator can survive the vibrations expected from travel, landing and take-off without any expected problem.   Shock. Figure 8(a) shows the accelerations obtained during the shock test in X axis using the free  fall machine. Similar results were obtained in Z axis. Figure 8(b) shows the accelerations obtained during the shock test in the Y axis using the pneumatic cannon. After the shock test, no anomalies were detected in the Dust Sensor, nor in the actuator subsystem. The levels in the  Y axis during the shock test are slightly below 2000g. In the initial calibration tests using a mechanical dummy model, the values obtained arrived at 2000g. Unfortunately in the QM test this value was not reached due to the variability of the method applied. As seen in Figure 8(b), the levels reached have several peaks during approximately 17 ms of duration, which is more restrictive than the single sinusoidal half-wave requested. Even though the values obtained demonstrate that the DS can support shock values near 2000g: no damage or defects were observed in the mechanical dummy model (that reached 2000g), neither in the QM of the DS.   Thermal cycling and vacuum test. Thermal vacuum cycling is a critical test for the rotary actuator  subsystem due to the complex thermal processes that take place during the huge thermal variation in vacuum (from -90ºC to +70ºC). During the test, several data from the sensors of the DS were logged. Also, more than 100 actuations over all the temperature range were logged. Figure 9 presents an actuation capture during the TVAC test at -90ºC. As it can be seen, due to the absence of thermal convection losses, the SMA fiber heats very fast (less than 300 ms) and takes more time during the cold down (~1.25 s).  

(a)                                                                        (b)  Figure 8. Results of shock test: (a) acceleration Vs Time obtained during the 500g shock test of  the DS; (b) acceleration Vs Time obtained during the 2000g shock test of the DS.
125 even contact points. Similarly, suitable tolerances have been assigned to moving part features in order to  avoid any jamming produced by the material expansion or contraction at extreme temperatures.             (a)                                                                      (b)  Figure 11. FEA results: (a) Pin Puller V.1 - shear load; (b) Pin Puller V.2 - shear load (right).   Finally, the response time has been computed, as part of the actuator analysis, for both Pin Puller versions. In order to fulfil the environment requirements (working temperature between -30ºC and 125ºC), wires with Austenite Start Temperature (A s) of 150ºC have been considered. Therefore, FEA have been  developed in order to obtain the temperature profile along the wire axis during operation and the actuator response time. The actuator maximum response time at worst case environment (-30ºC) has been estimated to be 4.3 s for version 1 and 2.8 s for version 2.      

                                        (a)                                                                          (b)  Figure 12. Built demonstrator of the both Arquimea Pin Puller versions: (a) devices of 500 N of  stroke force; (b) devices of 100 N of stroke force. 

Pin Puller as built Configuration  Demonstration models (DM) of both versions, Figure 12, were constructed in order to test the mechanical device concepts and to debug the design. The DMs have been constructed in Alumide material by rapid manufacturing process. Alumide is a composite of plastic and aluminum that provides a suitable resistance to prototypes for preliminary operation test. Moreover, this material does not conduct electricity that ensures the electrical insulation of the structure. Since the device reset is planned to be made manually by pulling the pin, a reset tool has been designed and built too. The reset tool can be recognized in Figure 12 next to the Pin Puller DM. Finally, the DMs contain commercial components, such as screws, cables, crimps and SMA actuators, for completing a successful demonstrator device of a Hold-Down and Release Mechanism. Figure 12(a) shows the demonstrator models of a Pin Puller with a stroke force of 500N. Good functional performances were obtained from both models. Promising performances
126 and some design concept improvements have been obtained for both versions of the device in this phase  of the development. The designs presented in this work can be easily scalable to different sizes and requirements. Figure 12(b) shows the demonstrator model of a Pin Puller with 100 N of stroke force, in which an engineering model (EM) is currently under development.  

Conclusions and Future Work 

Arquimea has characterized the proposed SMA material (SMARQ), demonstrating the material  capabilities to be used as a triggering actuator for space mechanisms. The material has shown a good behavior as Shape Memory Alloy. The project requirements in terms of operating temperatures, strain and force capabilities and lifetime have been satisfied.  A rotary actuator included in the QM of the DS for environmental conditions requirements of the MEIGA-MetNet Mission has been presented. DS will perform airborne dust opacity measurements on the Mars surface, as can be confirmed from the qualification campaign results obtained. The rotary actuator operational temperature range from -90ºC to +25ºC was an initial challenge that has been completely reached thanks to a correct thermal design and a proper control algorithm. The temperature range obtained exceeds the operational range presented for other SMA-based actuator for a Mars surface application as stated in [4].  Two complete Pin Puller mechanisms were conceptually designed and analyzed, with promising results. Demonstration models for both devices were constructed and tested, obtaining a successful proof of concept of the mechanisms. The results of the work presented show that SMARQ technology is ready to be used in the development of EM, QM and FM actuators for future space missions. Other potential applications are the design of actuators for multi-cycle operation, for working in hard environments, such as cryogenic applications, or for applications where an ultra-light weight is required. Finally, the technology developed during this project can be applied to other industrial applications outside the space market. 

References 

1. Duerig, T.W., Melton, K.N., Stockel D., and Wayman C.M. (Ed.). Engineering Aspects of Shape  Memory Alloys . London: Butterworth-Heineman, 1990.  2. Otsuka, K. and Wayman C.M. (Ed.). Shape Memory Materials . UK: Cambridge University Press,  1998.  3. Delaey, L. “Diffusionless Transformations”. Proceedings of Materials Science and Technology ,  (1991), Vol. 5, pp 339-404.   4. Fernández, D., Cabás, R. and Moreno, L. “Dust Wiper Mechanism for Operation in Mars”.  Proceedings of 12th European Space Mechanisms & Tribology Symposium (ESMATS),  (2007).  5. Jenkins P.P., Landis A.G. and Oberle L.G. “Materials Adherence experiment: Technology IECEC-  97339”. Proceedings of 32nd Intersociety Energy Conversion Engineering Conference,  (1997).  6. Collado, M., Martínez, D., Álvarez, F., Cabás, R., Moreno, L. and López, F. “Evolution of SMA Rotary  Actuators for Space Applications in Mars Environment”. Proceedings of Actuator 10 – International  Conference and Exhibition on New Actuators and Drive Systems , (2010).
128 from inside the fixed base tube. Latching features built into each tube allow the tubes to latch together as  the system is deploying and creating a stable structure once fully deployed. The latching features are explained below.  Stowed Design Features  The base tube is designed to support the tubes and STEM deployer for a typical spacecraft application. There are two sets of attachment points one at the base and one in the side close to the tip. Also there are graphite load rings at the tube tips to provide a stiff structure for supporting the payload. The stowed configuration of the TTM is shown in Figure 1.  

Figure 1.  Stowed TTM 

Deployment Design Features  There are three major components in the design to stabilize the TTM during its deployment. Each tube has three rails along the tube axis that are spaced 120 degrees apart to stabilize the rotation about the boom axis during the deployment. These rails also have secondary effects to increase the deployed stiffness. The second major component is a secondary stiffening ring at the base about one diameter apart from the latch ring to stabilize the rotations about the two lateral axes. Finally, there is one centralizer in each tube to support the STEM element and stabilize/improve its buckling capability. These main features of each tube that help stabilize the TTM during deployment are highlighted in Figure 2.   Figure 2.  Tube Features   Deployed Design Features  The deployed TTM has nonlinear stiffness mainly due to local flexibility of the latching feature. The stiffness increases as the applied loads to the latch-pin increases. Several design features have been implemented to increase the deployed stiffness. A load ring has been added to each tube tip where the latch-pins are engaged to stabilizes the local deformation of the thin walled tubes. As discussed earlier these load rings are part of launch restraint to support the payload during the launch. Also, the three
129 deployment rails along each tube add to the overall stiffness. Note that by pre-loading the latch-pins the  stiffness would be increased and the non-linearity could be reduced. For many applications, there may be a type of tension load which could pre-load the TTM; however, if needed the STEM deployer could be utilized to do this function.  STEM Deployer  The drive system for the TTM is a STEM deployer powered by a brushless dc motor which pushes against the tip plate. The STEM consists of a “C” section of thin formed metal that is flattened so it can be rolled onto a spool for launch, as shown in Figure 3. Deployable booms in the STEM family are simple and extremely lightweight; they have been successfully deployed over 300 times in space without any known failures.  

Figure 3.  STEM device used for TTM deployment/retraction 

The payload and package of stowed tube segments are pushed from the inside of the fixed external base tube by the STEM. When the package reaches the end of the fixed segment, the outer tube in the package latches to it. This tip deployment process repeats sequentially until all tubes are latched into place. The same sequence is reversed to retract. The innermost of the undeployed tubes is fixed to the tip of the STEM in order to stabilize the moving package of tubes.  

To minimize the number of tubes, they are all the  same length and are stowed coincident with each other. The latches fit in the annular gap between adjacent tubes in a stiffening ring at the lower end of each tube. The adjacent larger tube in turn necks down to a thin stiffening ring at the upper end. The stiffening ring helps to center and align the adjacent smaller tube and to lessen local deformations between the latched segments in bending.  Tube Latching  Small tapered pins are distributed circumferentially in the stiffening ring at the lower end of each tube. The pins are loaded radially outward by short springs to engage with tapered holes at the upper end of each larger adjacent tube, as shown in Figure 4. When stowed, the springs and pins are compressed by the interior surface of the adjacent larger tube. During  Figure 4.  Tapered pins used for latching
130 deployment, the tips of the pins slide on the surface until they pop into the tapered seats to latch.   Sequencing  Since the tubes are stowed coincident to each other, each ring of compressed latch pins can engage the adjacent smaller ring with simple detents as shown in Figure 4. All the nested tubes are thus locked together so that they can be pushed as a package during deployment. When the latch ring in the outermost tube of the pack age locks it into deployed structure, t he detents retaining that tube to the  moving package of tubes are released. The now smaller package of moving tubes continues without interruption.  The male component of the detent on the interior end of the latch pin is conically shaped to make the latching function fail-safe. If one or more springs fail, the affected pin is forced out of the way by the female side of the detent, which acts as a ramp, as shown in Figure 4. Without the spring to preload the pin in the tapered receptacle, that pin cannot contribute to the deployed stiffness of the boom, however, deployment will not be impeded.  Retraction  To retract a given tube, its latch pins are pulled from engagement with the next larger tube by ramps in the next smaller tube. The ramps are hollowed out of the latch rings to engage conical rims at the male detent end of the latch pins, as shown in Figure 5.  Latch pins are alternated with retraction ramps and detents in increments around the circumference of each ring. Each successive tube in the assembly is indexed by one such increment relative to its neighbors so that everything meshes properly. The length of the trough is controlled so that the detents will engage before the deployed tube is unlatched, as shown in the second inset of Figure 5.    

   Figure 5.  Boom retraction sequence
131  TTM Special Design Case  

In order to study and evaluate the feasibility of utilizing the TTM concept for long boom applications, a special design case was selected in 2005 which was later built and tested. The key parameters and top level requirements for this design are:     Deployed length of 34.3 m (1350 in) from bottom of base to tip   Stowed length of 2.16 m (85 in)     Mass is approximately 58 kg (128 lb)   Deploy time within 14 minutes   Stowed frequency should be greater than 35 Hz    Deployed frequency should be greater than 0.1 Hz    Mast should be able to retract by reversing motor   Tip displacement during the deployment/retraction should stay within ±17.8 cm (7 in)    Tube Properties  There are 17 telescoping tubes, excluding the fixed base tube. Table 1 lists properties for the minimum and maximum diameter telescopic tubes, along with Tube 9 which is the tube in the middle between the base and the tip. Tube 1 is the tube closest to the base tube and is 31.8 cm (12.5 in) diameter, while Tube 17 is the last tube at the tip and is 11.4 cm (4.5 in) diameter. Listed in the table are the different stiffness properties for each of the tubes. EI is the bending stiffness of the tube, GJ is the torsional stiffness of the tube, and EA is the axial stiffness of the tube.   Table 1.  Tube Properties 

Tube Tube  Diameter  (cm) Thickness  (mm) EI (x103 N·m2) GJ (x103 N·m2) EA (x106 N) Mass/Length  (kg/m)  1 (Max) 31.8 0.51 868.9 346.9 69.0 1.56  9 21.6 0.38 140.3 105.8 24.1 1.47  17 (Min) 11.4 1.02 81.1 41.9 49.6 1.93     Stowed Frequency Analysis   A stowed finite element model of the TTM was created to compute the natural frequencies. The fundamental computed natural frequency is 37.88 Hz which exceeds the 35 Hz requirement. The first ten stowed natural frequencies are listed in Table 2 and the first three mode shapes are shown in Figure 6. Note that these frequency results have not been validated by a test.  

Figure 6.  First three modes in the stowed configuration