Multibody dynamics for biologically inspired smart space structure

Structures in space are often just serving a single purpose. By developing a structure which is able to change it properties and adapt to changing environmental conditions, the costs of space missions can be decreased significantly. The design and simulation of such a structure is presented in this paper. The developed structure consists of an array of interconnected cells which are each able to alter their volume due to internal pressure change. By coordinated cell actuation in a specific pattern, the global structure can be deformed to obtain a desired shape. A multibody code was developed which constantly solves the equation of motion with inputs from internal actuation and external perturbation forces. During the inflation and actuation of the structure, the entities of the mass matrix and the stiffness matrix are changed due to changing properties of the cells within the array based on their state and displacement. This paper outlines the principles behind the developed code and gives examples in two dimensional and three dimensional space

Inflatable structures for Mars Base 10

A permanent manned settlement on the Martian surface requires the use of advanced technology concepts in order to become technically and financially feasible. The former developed Mars Base 10 concept incorporates novel ideas, increasing the feasibility of a continous human base on Mars. The most advanced feature of the MB10 design is the concept of increasing the habitable space of the Mars base once landed with an inflatable torus like structure. This paper gives an overview on the MB10 design and has its primary focus on the deployment of the inflatable structure. The deployment simulations show the final inflated shape of the MB10 concept on Mars from an un-inflated initial shape on Earth. The deployment strategy, simulations and rigidization techniques are discussed to provide a conceptual solution for large inflatable components of the MB10 habitat. Further applications of secondary inflatable smart structures are presented as well. These secondary structures are self deploying at the Martian ambient pressure which results in low storage volume and mass. These structures are well-suited to carry on for astronauts on EVAs for example

Deployment simulation of very large inflatable tensegrity reflectors

Propulsion, energy collection, communication or habitation in space requires ever larger space structures for the exploration of our solar system and beyond. Due to the payload size restrictions of the current launch vehicles, deployable structures are the way to go to launch very large structures into orbit. This paper therefore presents the design and simulation of a tensegrity based structure with inflatable rigidizable tubes as compression struts. The literature review showed that inflatable structures are most promising for the development of deployable reflectors larger than twenty meters in diameter. Good compression performance and reliability can be achieved by employing rigidisable inflatable tubes. The concept presented in this paper will focus on the development and simulation of a one meter diameter hexagonal reflector substructure that can be easily expanded to larger diameters due to its modular design. The one meter diameter modular approach was chosen to be able to build a full size benchmark model to validate the numerical data in the future. Due to the fact that the tensegrity compression elements are not initiating at one specific location, a passive reaction gas inflation technique is proposed which makes the structure independent of any pumps or other active inflation devices. This paper will discuss the use of inflatable rigidizable elements and their counteraction with the rest of the tensegrity structure. Simulations have been undertaken to capture the deployment behaviour of the inflating tube while getting perturbated by the attached tensegrity tension cables. These simulations showed that the use of inflatable rigidisable struts in tensegrity assemblies can greatly decrease the system mass and stowed volume, especially for very large reflectors compared to conventional approaches

Bio-inspired programmable matter for space applications

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. An idea presented in this paper 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. This paper will outline the design idea and fabrication of the bio-inspired membrane and its application to space missions. Deployment simulations were undertaken in LS-DYNA™ and compared to bench test samples of vacuum inflating circular specimens. A model to control the local elements in order to obtain a desired global shape will be presented as well. The paper will conclude with an overview on the REXUS 13 sounding rocket experiment StrathSat-R which will deploy a prototype of the bio-inspired adaptive membrane in micro gravity in spring 2013

Development of an Adaptive Flap/Flaperon Flight Control System with Shape Memory Alloy Actuation

This thesis discusses the design, manufacturing and testing of a new kind of adaptive airfoil using Shape Memory Alloy (SMA) actuation. An antagonistic arrangement of SMA wires was used in a Post-Buckled Precompressed (PBP) kind of actuator that was employed in an adaptive flap system. The thesis opens with a short survey on the history of the PBP mechanism and a literature research on different flap systems actuated by adaptive materials. The conceptual design of the SMAPBP actuator and its evolution to the actuator employed in an adaptive aerostructure is discussed in the first chapters. Experiments showed that the SMAPBP actuator could obtain tip rotations up to 65°, which nearly quadrupled the levels achieved by piezoelectric PBP actuators. In the following, former developed theory for piezoelectric PBP actuators was modified to account for the trapezoidal shape of the SMAPBP actuator. The developed theory was then compared to experimental results. A FEM model was also developed and evaluated to prove the PBP concept for this actuator numerically. In the second section of the thesis the author gives a detailed explanation of the design concept and the manufacturing of the airfoil. A NACA0012 airfoil with a chord length of 150mm and a width of 100mm was used to prove the concept of the adaptive flap system. The thesis continues with a description of the test setup, the CFD model assumptions and the results of wind tunnel tests. The developed adaptive airfoil proved its capabilities during the numerical and experimental tests and showed that the employment and actuation of the SMAPBP actuator could more than doubled the lift coefficient of the airfoil. The architecture and employment of a closed loop position feedback system to overcome the nonlinear behavior of the SMA material and the PBP mechanism is also discussed. The thesis closes with an overview over the adaptive airfoil with SMAPBP actuator and gives recommendations for future work in this field

StrathSat-R : Deploying inflatable CubeSat structures in micro gravity

This paper presents the concepts, objectives and design of a student-led sounding rocket experiment which shall test novel inflatable devices in space conditions. This experiment is envisaged as the first step towards developing a CubeSat programme at the University of Strathclyde, which can exploit the novel concepts developed and the technical skills gained. The experiment itself aims to test novel, student developed, inflatable space structures in micro gravity and reduced pressure conditions. It consists of three distinct sections, the ejection housing on the rocket and the two ejectable modules that are based on CubeSat architecture. Shortly before reaching apogee, the two modules are ejected from the rocket and will deploy their own inflating structure during free flight. After landing, the ejectable modules recovery will rely upon a GPS position relayed to the team from the module by Globalstar transmission and a RF beacon for tracking with the recovery helicopter. The two modules carry two different structures resulting in distinct mission objectives: The aim of FRODO is to deploy an experimental passive de-orbiting system for high altitude spacecraft which will in the future utilise solar radiation pressure for orbit removal. The aim of SAM is to serve as a technology demonstrator for the residual air deployment method of a smart bio-inspired space structure. This paper contains details about the science objectives of the mission and how they will be achieved, its experimental design and the management of the student-led project

Design, Manufacturing and Test of a High Lift Secondary Flight Control Surface with Shape Memory Alloy Post-Buckled Precompressed Actuators

The use of morphing components on aerospace structures can greatly increase the versatility of an aircraft. This paper presents the design, manufacturing and testing of a new kind of adaptive airfoil with actuation through Shape Memory Alloys (SMA). The developed adaptive flap system makes use of a novel actuator that employs SMA wires in an antagonistic arrangement with a Post-Buckled Precompressed (PBP) mechanism. SMA actuators are usually used in an antagonistic arrangement or are arranged to move structural components with linearly varying resistance levels similar to springs. Unfortunately, most of this strain energy is spent doing work on the passive structure rather than performing the task at hand, like moving a flight control surface or resisting air loads. A solution is the use of Post-Buckled Precompressed (PBP) actuators that are arranged so that the active elements do not waste energy fighting passive structural stiffnesses. One major problem with PBP actuators is that the low tensile strength of the piezoelectric elements can often result in tensile failure of the actuator on the convex face. A solution to this problem is the use of SMA as actuator material due to their tolerance of tensile stresses. The power consumption to hold deflections is reduced by approximately 20% with the Post-Buckled Precompressed mechanism. Conventional SMAs are essentially non-starters for many classes of aircraft due to the requirement of holding the flight control surfaces in a given position for extremely long times to trim the vehicle. For the reason that PBP actuators balance out air and structural loads, the steady-state load on the SMAs is essentially negligible, when properly designed. Simulations and experiments showed that the SMAPBP actuator shows tip rotations on the order of 45°, which is nearly triple the levels achieved by piezoelectric PBP actuators. The developed SMAPBP actuator was integrated in a NACA0012 airfoil with a flexible skin to carry out wind tunnel tests

Results of REXUS12's Suaineadh Experiment : Deployment of a spinning space web in micro gravity conditions

On the 19th of March 2012, the Suaineadh experiment was launched onboard the sounding rocket REXUS12 (Rocket Experiments for University Students) from the Swedish launch base ESRANGE in Kiruna. The Suaineadh experiment served as a technology demonstrator for a space web deployed by a spinning assembly. The deployment of this web is a stepping stone for the development of ever larger structures in space. Such a structure could serve as a substructure for solar arrays, transmitters and/or antennas. The team was comprised of students from the University of Strathclyde (Glasgow, UK), the University of Glasgow (Glasgow, UK) and the Royal Institute of Technology (Stockholm, Sweden), designing, manufacturing and testing the experiment over the past 24 months. Following launch, the experiment was ejected from the ejection barrel located within the nosecone of the rocket. Centrifugal forces acting upon the space webs spinning assembly were used to stabilise the experiment’s platform. A specifically designed spinning reaction wheel, with an active control method, was used. Once the experiment’s motion was controlled, a 2 m by 2 m space web is released. Four daughter sections situated in the corners of the square web served as masses to stabilise the web due to the centrifugal forces acting on them. The four daughter sections contained inertial measurement units (IMUs). Each IMU provided acceleration and velocity measurements in all three directions. Through this, the positions of the four corners could be found through integration with respect to known time of the accelerations and rotations. Furthermore, four cameras mounted on the central hub section captured high resolution imagery of the deployment process. After the launch of REXUS12, the recovery helicopter was unable to locate the ejected experiment, but 22 pictures were received over the wireless connection between the experiment and the rocket. The last received picture was taken at the commencement of web deployment. Inspection of these pictures allowed the assumption that the experiment was fully functional after ejection, but perhaps through tumbling of either the experiment or the rocket, the wireless connection was interrupted. A recovery mission in the middle of August was only able to find the REXUS12 motor and the payload impact location

SmallSat Space Solar Power: A Pathway to a Sustainable Future

On the 29th of July, 2019, humanity had already used more resources than the Earth regenerated in the entirety of the year. This is while 13% of people do not have access to electricity, and 40% do not have access to clean energy for cooking. Simply put, the Earth cannot sustain humanity’s energy needs