대형 구조물 전개장치용 초탄성 형상기억합금 기반 고댐핑 적층형 테이프 스프링 힌지의 기능 검증에 관한 연구

Abstract

When a satellite is launched, it is mounted on a launch vehicle, and is then launched and operated to the mission orbit. However, since the inside of the projectile is limited, the bulky payload mounted inside the satellite is mainly designed/manufactured and mounted as a deployable structure. A representative structure among these deployable structures for satellites is a deployable solar panel. The solar panel increases the power required of the system due to the advancement/diversification of satellite missions, thereby causing an increase in the size and volume of the solar panel. Recently, not only simple deployable solar panels but also multiple deployable solar panels have been applied to satisfy power requirements. However, the increase in the size and volume of the deployable solar panel causes residual vibrations in the solar panel due to the attitude movement of the satellite, the rotational driving of the deployment driving type solar panel, and thermal shock. In addition, deployment of a deployable solar panel is required to perform a mission when a satellite arrives in orbit, and the deployment shock generated at this time is transmitted to the satellite through a hinge. On the other hand, a hinge mechanism is applied to the deployable solar panel for storage when the satellite is mounted and for smooth mission performance on orbit. Hinges proposed so far are largely classified into articulated hinges, flexible hinges, and cable hinges. The articulated hinge is applied with a fixing mechanism and a pin joint, a torsion spring for deployment, and a stopper to prevent collision between the deployable solar panel and the satellite. In addition, the articulated hinge has excellent post-deployment rigidity and minimizes the deployment shock as it is easy to install damping equipment and fixing equipment, but the mechanism is complicated and occupies a relatively large volume. A representative example of a flexible hinge is a tape spring hinge, which can be implemented with only a few tape springs, so a relatively simple system, light weight, low cost, and deployment reliability are guaranteed. However, as a large deployment torque is required when the tape spring hinge is applied for the deployment of a large structure, the aforementioned deployment shock occurs. The impact affects the damage of the hinge part and the internal electronic equipment. The cable hinge is mainly applied to multi-deployable structures, and the unfolding process of the applied hinge can be controlled through the cable loop. In addition, the hinge is advantageous in maintaining rigidity after deployment of the deployable structure, but has a disadvantage in having a complicated system according to cable loop driving. Residual vibrations generated by the posture maneuver of the satellite, rotational driving of the deployment-driven solar panel, thermal shock, etc., and the deployment shock generated when the deployment-type structure is deployed are transmitted to the satellite by the hinge mechanism. The residual vibration delays the posture stabilization time of the satellite or affects the viewing angle of the camera when transmitted to the optical payload. As shown in Figure 1, it acts as a major factor that causes deterioration of the image quality of high-resolution observation satellites. In addition, the impact generated during deployment affects the damage of the hinge part and internal electronic equipment, and may cause mission failure of the satellite. In order to overcome these shortcomings, studies on high-rigidity hinges and hinges for impact reduction were conducted in previous studies. However, in the case of the hinges, only studies have been conducted on the reduction of deployment shocks that occur during deployment, and there is no research on hinges capable of reducing residual vibration. In this study, we focused on the superelastic properties of SMA for the design to reduce the impact of deployment when deploying a deployable solar panel. The superelastic properties refer to the properties of restoring to the original shape without residual stress when the load is removed even when the shape is deformed by an external load at a temperature higher than the initially set austenite finish (Af) temperature of the SMA. Superelastic SMA has the advantage of high damping and restoration properties compared to general metals, so various studies have been carried out in the aerospace industry as well as in general industries such as medical, automobile, and aviation. In addition, attention was paid to the high damping characteristics of the constrained layer laminated structure to which the viscoelastic tape was applied in order to realize the reduction of residual vibration and deployment shock occurring in the deployable solar panel. A number of previous studies have demonstrated the damping performance of a viscoelastic material-based laminated structure. In this study, a superelastic SMA high damping laminated tape spring hinge that combines the superelastic SMA effect and a laminated structure with viscoelastic tape was proposed. The hinge simply applies a super-elastic SMA plate to the hinge of the tape spring, so that it is possible to reduce the deployment shock generated during deployment of the deployable solar panel. In addition, by laminating the viscoelastic tape on a thin sheet to which the viscoelastic tape is applied on the upper and lower parts of the superelastic SMA plate, it is possible to reduce the residual vibration generated during high satellite motion. In addition, specimens for testing were prepared to validate the design of the proposed hinge. In addition, a free damping test was performed to identify the characteristics of superelastic SMA and reduce residual vibration according to the number of layers. In addition, a deployment shock test was performed to understand the reduction in deployment shock that occurs during deployment. From the test results conducted in this study, it was demonstrated that the vibration/shock reduction was achieved compared to the tape spring hinge to which the superelastic SMA plate was not applied due to the high damping performance when the super-elastic SMA high-damping laminated tape spring hinge was applied.| 위성은 발사체 페어링 내부 크기가 제한적임에 따라 대형 구조물의 경우 전개 메커니즘이 적용되어 발사 시 수납 및 궤도상에서 임무 수행을 위해 전개된다. 전개 메커니즘은 일반적으로 간단한 설계, 경량, 저비용 및 전개 신뢰성이 보장되는 테이프 스프링 힌지가 주로 적용되고 있다. 그러나 대형 구조물 전개를 위해 테이프 스프링 힌지는 큰 전개 토크가 요구됨에 따라 전개 충격 증가가 야기된다. 아울러, 위성 고기동 시 태양전지판의 잔류진동으로 인해 위성의 자세안정화 시간을 지연시키거나 카메라 시선각 교란에 따른 관측목표 지향 성능 저하 등을 초래한다. 본 연구에서는 상기 단점을 극복하기 위해 일반 금속재질 대비 고댐핑 특성 구현이 가능한 초탄성 형상기억합금에 점탄성 테이프를 통해 얇은 박판을 적층한 구조를 적용한 테이프 스프링 힌지를 제안하였다. 상기 제안한 힌지에 대한 기본특성 파악을 위해 변위에 따른 자유감쇠시험, 전개충격시험을 통해 설계 유효성을 입증하였다.