Performance investigation of a novel pseudoelastic SMA mesh washer gear wheel with micro-jitter attenuation capability

Abstract

A stepper-actuated mechanism, such as a gimbal type antenna, is a major source of micro-jitters that affect the image quality of a high-resolution observation satellite. Attenuating micro-jitter disturbances induced by a stepper motor activation is one method of enhancing image quality of an observation satellite. In this study, we propose a novel gear with micro-jitter attenuation capability for stepper-actuated mechanism. This can be achieved by implementing a pseudoelastic shape memory alloy mesh washer on the gear wheel. This application makes it possible to achieve the gear with lower torsional stiffness and higher damping in the torsional direction of the gear, whose characteristics will assist in resolving the micro-jitter attenuation issues of a gear. The effectiveness of the gear proposed in this study was demonstrated by numerical simulation and jitter measurement tests using the gimbal type antenna mechanism actuated by the stepper motor.

Experimental Validation of Fly-Wheel Passive Launch and On-Orbit Vibration Isolation System by Using a Superelastic SMA Mesh Washer Isolator

“…The density and mass of the mesh washer were 1.7 g/cm 3 and 1.88 g. The density was 50% lower than that of the mesh washer used by Youn et al [18] and Oh et al [16,17,22]. Figure 2 shows an example of the representative static test results of the SMA mesh washer shown in Figure 1 during compressive loading and unloading in the thickness direction of the washer [21]. The test results indicate that a largely deformed SMA mesh washer in the thickness direction with a displacement of 2.5 mm can recover its original shape without plastic deformation upon unloading due to its pseudoelastic or superelastic SMA characteristics.…”

“…In the previous study, the effectiveness of the new application form of the SMA mesh washer using a radial direction of the ring-type mesh washer was investigated [21,22]. Kwon et al proposed a novel pseudoelastic gear that utilized the ring-type SMA mesh washer as a spring-blade to bridge the output shaft of the motor with an existing gear wheel [21].…”

“…Kwon et al proposed a novel pseudoelastic gear that utilized the ring-type SMA mesh washer as a spring-blade to bridge the output shaft of the motor with an existing gear wheel [21]. This application was researched and developed for attenuating the micro-jitter induced by stepper motor activation of the twoaxis gimbal antenna.…”

“…To achieve a passive launch and on-orbit vibration isolator that does not require a hold and release mechanism, we focused on the superelastic behavior of the compressed SMA mesh washer as shown in Figure 1 [21]. The SMA mesh washer was manufactured by pressing a knitted wire mesh by using a mold of the required shape.…”

“…From the above sine vibration test results, it can be seen that the highest acceleration response obtained from each of the -, -, and -axes, when corresponded axis excitation was induced to the RWA isolation system, did not exceed the RWA's design load of 42.1 g, guaranteeing the structural safety of the RWA and isolator itself under sine vibration loads without requiring an additional launch-locking device. However, this design approach cannot be achieved using stainless-steel wire mesh as this material exhibited plastic deformation after a compressive displacement of 0.5 mm [21]. In addition, because of the relatively higher stiffness value of the steel washer within the elastic range, the jitter isolation capability might be degraded because the isolation capability heavily depends on the stiffness value.…”