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- Mallol Parera, Pau, 1980-
(författare)
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Deployment Simulations of a Composite Boom for Small Satellites
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The use of small satellites is rapidly growing, especially satellites with masses between 1 and 10 kg and few litres of volume. The main reasons are due to the low development time and cost. Electronics miniaturization and high density integration is enabling the small satellites class to perform more and better tasks and at a lower cost. When deployable structures are required for the missions, the actual paradigm is that there are very few that have been successfully developed and flown. It is usually not possible to scale down existing deployable structures from larger satellites. Power and attitude control is also very limited in small satellites thus, completely new deployable structures, low mass and with high packaging ratio (yet large and with adequate mechanical properties when deployed) must be developed. Furthermore, such new structures are usually made of very thin and light materials which complicates the on-ground tests prior the launch. Therefore, advances in modelling and simulation deployable structures such as booms are also of great interest for the scientific community.This thesis and the papers included herein focus on the finite element modelling of a meter-class passively deployable boom – based on the SIMPLE boom by Thomas W. Murphey – and deployment simulations. Experimental tests were also carried on a boom prototype suspended from a gravity off-loading system. An analytical model produced certain parameters which are used for validation of the finite element model. The strain energy stored in the boom prior to deployment and spacecraft displacements during deployment agreed well. The deployment time, however, have discrepancies: the models predicted a deployment time six times faster than the experimental tests. For that reason the deployment simulations cannot be compared with the tests. The reason of the discrepancies are believed to be due to the actual material model and the contacts formulation used in the finite element model. The finite element simulations, however, shows a reasonable behaviour given the nature of the deployment thus, despite the necessary improvements, we believe that future improvements in the material and friction models will provide us more realistic results.
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| 2. |
- Takahashi, H., et al.
(författare)
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A thermal-neutron detector with a phoswich system of LiCaAlF6 and BGO crystal scintillators onboard PoGOLite
- 2010
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Ingår i: 2010 IEEE Nuclear Science Symposium, Medical Imaging Conference, NSS/MIC 2010 and 17th International Workshop on Room-Temperature Semiconductor X-ray and Gamma-ray Detectors, RTSD 2010. ; , s. 32-37
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Konferensbidrag (refereegranskat)abstract
- To measure the flux of atmospheric neutrons and study the neutron contribution to the background of the main detector of the PoGOLite (Polarized Gamma-ray Observer) balloon-borne experiment, a thermal-neutron detector with a phoswich system of LiCaAlF6 (Eu) and BGO crystal scintillators is developed. The performance to separate thermal-neutron events from those of gamma-rays and charged particles is validated with 252Cf on ground. The detector is attached to the PoGOLite instrument and is launched in 2011 from the Esrange facility in the North of Sweden. Although the emission wavelength of the LiCaAlF6 (Ce) is 300 nm and overlaps with the absorption wavelength of the BGO, the phoswich capability of the LiCaAlF6 (Ce) with the BGO is also confirmed with installing a waveform shifter.
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