Deploy-able Smart Space Structures
Funder University of Strathclyde
Period October 2010 - December 2013
Project PI Massimiliano Vasile
Background
Space vehicle size is nowadays mainly governed by launch vehicle dimensions. The use of deployable structures became necessary due to their low stowage and high in-orbit volume. For the success of future space missions involving large space structure, the development of new deployable structures and the improvement of current designs are of great importance. Applications can be easily envisioned through space based solar power systems, truss structures, masts, crew quarters, transport tunnels, large solar arrays, solar concentrators, solar sails or antennas. A valuable option for these large ultra light structures is the exploitation of inflatables. Reasons for the use of inflatable structures range from their low cost over exceptional packaging efficiency, deployment reliability, low stowage volume to low weight. Despite the fact that there has been no major leap on inflatable structure in space since the IN-STEP Inflatable Antenna Experiment in 1998, research has been undertaken in various institutions all over the world in the field of inflatable structures; new membrane materials have been discovered that can withstand the space environment, advanced simulation tools were developed that capture the highly non-linear behaviour of the inflation process and rigidization techniques have been investigated making the structure non-reliant on the inflation gas after deployment.
Executive Summary
Nowadays, space structures are often designed to serve only a single objective during their mission life, examples are solar sails for propulsion, antennas for communication or shields for protection. By enabling a structure to change its shape and therefore adapt to different mission stages in a single structure, the flexibility of the spacecraft can be increased by greatly decreasing the mass of the entire system. The possibility to obtain such a structure lies in a cellular approach in which every cell is programmable to change its basic properties. The shape change of the global structure can be significantly by adding up these local changes, for example the cells length. The idea is to adapt these basic changeable elements from nature’s heliotropism. Heliotropism is the growth or movement of an organism towards the direction of the sunlight. By changing the turgor pressure between two adjacent cells in the plant’s stem, called motor cells, the stem of the plant flexes. Due to the simplicity of the principle, the movement through pressure change seems perfect for the application on deployable space structures. The design of the adaptive membrane consists of an array of cells which are inflated by employing residual air inflation. Residual air inflation uses the expansion of trapped air inside the structure when subjected to vacuum conditions to inflate the structure. A high packing efficiency and deployment reliability can be achieved by using this passive deployment technique coupled with a multiple unit membrane design. To imitate the turgor pressure change between the motor cells of the plants to space structures, piezoelectric micro pumps are added between two neighbouring cells. The smallest actuator unit in this assembly is therefore the two neighbouring cells and the connected micro pump. The cellular and multiple unit approach makes the structure highly scalable with countless application areas. Deployment simulations were undertaken in LS-DYNA™ and compared to bench test samples of vacuum inflating circular specimens. Current research is focused on establishing a dynamic model to simulate the actuation potential of the adaptive membrane and its controllability.
LS-DYNA™ simulation of fully inflated adaptive array consisting of 38 cells
Key Publications
Other Resources
Related experiments:
Related Projects
Distributed and Heterogeneous Swarm Engineering
UKube-1
Next Generation CubeSat
ESEO
