HEHG developed the "expandable flexible solar cell system based on the structure of shape memory polymer smart composite material". On December 27, 2019, it carried the Shishi 20 satellite developed by the China Academy of Space Technology successfully with the Long March 5 rocket in Wenchang, Hainan Flying. As one of the main tasks of the satellite, the system successfully completed the key technology test on January 5, 2020, and realized the on-orbit controllable deployment of flexible solar cells based on the shape memory polymer composite structure for the first time in the world. The group believes that it solves the problem of ground curling and locking of flexible solar cells-controllable deployment on rail-high rigidity and bearing capacity after deployment.
As one of the key components of aerospace vehicles, solar cells usually need to go through the four steps of "manufacturing on the ground-folding and gathering-launching into space-space unfolding" before they can work in orbit. The next generation of large or super large space structures puts forward extremely high requirements on energy systems. As one of the new trends in the development of solar cells, flexible solar cells have the advantages of light weight, good flexibility, and high storage ratio. However, in the process of aerospace application There are also difficulties in folding and locking, driving expansion and low stiffness after expansion.
The HEHG Institute of Composite Materials and Structures established the research direction of smart materials and structures earlier in China in the early 1990s. The project team has been engaged in research on the structural mechanics of smart materials and their applications in aerospace, aviation, biomedicine and other fields. Beginning in 2006, the project team has carried out research on the structure of shape memory polymers and their composite materials, and independently developed various types and series of shape memory polymer materials suitable for aerospace environments. These materials can meet different extreme space environments such as high and low orbits. Demand. Different from Shape Memory Alloy (Shape Memory Alloy), Shape Memory Polymer (Shape Memory Polymer) is an excitation-response polymer material with active and controllable large deformation (20%-500%), diverse driving methods, and variable stiffness It can be designed as a component that integrates driving and bearing functions, with simple structure and high reliability. It is expected to partially replace the complex electromechanical driving system in the future.
The “expandable flexible solar cell system based on a shape memory polymer smart composite structure” carried this time mainly includes a shape memory composite material lock release mechanism developed by HEHG, a shape memory polymer composite material expandable beam and Shanghai Space Power Flexible thin-film solar cells developed by the institute. Based on the mechanics theory of composite materials and the refined design of the structure, the shape memory polymer composite structure can realize the functions of locking, releasing and unfolding the flexible solar cell, as well as high rigidity and bearing capacity after unfolding. During the launch of the satellite, the shape memory composite material locking release mechanism can provide and realize high rigidity locking; after entering the orbit, it can complete the on-orbit stable and impact-free unlocking; during the deployment process, the shape memory polymer composite material can be deployed The controlled extension of the beam drives the expansion of the flexible solar thin-film battery; after unfolding, the stiffness of the shape memory polymer composite beam structure returns to a level equivalent to that of the conventional composite structure, and the fundamental frequency of the expanded state is higher, providing high rigidity bearing Features. The deployable flexible solar cell system carried this time realizes the functions of locking, releasing and structural expansion through the structure of the shape memory polymer composite material. It does not use traditional pyrotechnic separation devices, hinges and motor drive methods, and has a simple structure. The unlocking and unfolding process has almost no impact, the unfolding time and process are controllable, and the rigidity of the structure after unfolding is high.
With the strong support and help of the Communications Satellite Division of the China Academy of Space Technology, the "flexible solar cell system based on the shape memory polymer smart composite structure" was successfully verified in orbit on January 5, 2020, which is the continuation of 2016 After HEHG achieved the on-orbit verification of the shape memory polymer composite material in the geosynchronous orbit environment for the first time in the world, it realized the on-orbit controllable deployment of the flexible solar cell system based on the shape memory polymer composite material structure for the first time in the world. The success of the second on-orbit mission indicates that China's research on smart materials and spacecraft structures is at the forefront of the world. Based on the previous technology accumulation, the smart structure based on shape memory polymer composite materials will also be applied to China's first Mars exploration mission-"Tianwen-1". In the future, related technologies are also expected to be applied to space expandable structures, lock release mechanisms and flexible solar cell systems in different spacecraft platforms such as deep space exploration, space stations, lunar exploration projects, satellites, etc., in aerospace, aviation, automobiles, and high-end equipment , Intelligent manufacturing, robotics and biomedicine have broad application prospects.