In the global aerospace industry, the demand for small satellites to verify space science technology at low cost is recently increasing. However, the payload volume is limited due to the small size of the satellite, and it affects the payload size and mission performance. To overcome this limitation, the utilization of deployable structures in space structures is gaining attention. In this study, we propose an 8U CubeSat structure concept that can be separated into upper 4U and lower 4U in orbit. A flat-retractable truss structure, which has a compact storage volume and high stiffness compared to other deployable structures, is used for separation between upper and lower units. To confirm the feasibility of the proposed structural concept, a CubeSat structure prototype is manufactured. Imaginary optical payload is assumed to be mounted and the optical performance of this concept is theoretically analyzed. In addition, a membrane shield concept in the form of an origami-based Bellows patterned cylinder is designed to prevent the light disturbance and thermal deformation of the deployable structure. Finally, the unit-separable 8U CubeSat structure integrated with the shield structure was presented.
This paper proposes a concept of a deployable tubular structure with the Yoshimura pattern based upon a novel folding approach. The developed folding approach is based on the reconfiguration of the Yoshimura tubular structure into the intermediate configurations. All the possible candidates of the intermediate configurations are derived with respect to the design parameters. The structural behavior during the reconfiguration process is analyzed to figure out the driving force for the deployment and the stability of the structure. The deployment of the Yoshimura tubular structure is demonstrated through the prototype with active hinges made with shape memory plastic.
As the demand for microsatellites increases, deployable structures have been used to increase mission performances of microsatellites. Tape spring based deployable structures are lightweight and they can be constructed to have high packaging efficiency; they are suitable for microsatellites. This paper presents a meter-class deployable structure for microsatellite using tape spring. This structure is stowed in a volume of 1U CubeSat and after deployment it has an area of 1m2 with natural frequencies over 10 Hz. Modal analysis was performed to check the stiffness requirement after deployment. Deployment tests were performed to validate the deployment reliability, and the deployment accuracy.
There has been increasing demand for larger space structures to satisfy the requirements of astrophysics missions. However, storage space for payloads in satellites is limited, so deployable structures are used in most space missions to minimize storage space and consequently, to reduce launch costs. This work proposes a deployable truss structure which can improve the packaging efficiency of the existing truss structure. The main feature of the proposed structure is that it can be stored in a flat form. Each unit consists of Scissor-like Elements (SLEs) and the whole structure is deployed in a three-dimensional form with a simple mechanism. The detailed configurations and mechanism of the proposed structure are discussed. The geometric constraints for folding the proposed structure into a planar form were analyzed. A kinematic analysis to describe the motion of the structure was also performed. Then the packaging efficiency with respect to length, which is an important performance index of such deployable structures, was analyzed and compared with a typical truss structure.
Recently, space structures are getting larger and more complex because of the more demanding requirements in the space mission. Constructing large structures in space has several challenging issues such as assembly, maintenance and delivering cost. Deployable structures can be the appropriate solution to construct large space structures. Employing bistable characteristics can provide additional advantages to the deployable structure for solving these issues because the overall system can be made relatively simple as well as reliable. In this study, a new concept of the deployable structure using bistable characteristics is proposed. Due to the bistability, both folded and deployed states of the proposed deployable structure can stay under the stable state. The mathematical model of the single bistable component is established to analyze the effect of the off-axis ratio on the characteristics of the proposed structure. In order to analyze the deployment behavior of the proposed structure, the dynamic model of the single bistable component is established. The driving force from the SMA spring is measured from an experiment. By applying the force profiles to the dynamic model, the simulation of the proposed structure is conducted. In order to validate the dynamic model, the experimental model is constructed and the deployment process is captured. The comparison of the simulated and experimental results shows good agreement.
In this study, the use of the twisted string concept with a pin, serving as a moment arm, is proposed to produce the snapthrough of a pre-compressed beam so that the whole system can be used as an effective on/off actuator. The twisted string mechanism is to produce a horizontal pulling force to the pin, which triggers the snap-through of the beam. The actuation moment required to trigger the bistable beam in this study is 24.3 Nmm, corresponding to a horizontal force of 0.81 N. The twisted string actuator is able to produce a pulling force of 1 N, which is further pulled through a distance of 5-mm. Static performance of the integrated system based on the effects of the length of the string on the required input motor voltage, torque, and the overall system response time is experimentally investigated. The snap-through sequence during the static experiment is also captured with a high-speed camera. The input voltage to the motor increases as the length of the string is increased. The length of the string also affects the overall system response, motor speed and torque. The whole snap-through of the beam happens within 100 msec after the trigger signal is sent.
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