| 1. |
- Mao, Huina, et al.
(författare)
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Deployment of Bistable Self-Deployable Tape Spring Booms Using a Gravity Offloading System
- 2017
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Ingår i: Journal of Aerospace Engineering. - Journal of Aerospace Engineering. - 0893-1321 .- 1943-5525. ; 30:4
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Tidskriftsartikel (refereegranskat)abstract
- Bistable tape springs are suitable as deployable structures thanks to their high packaging ratio, self-deployment ability, low cost, light weight, and stiffness. A deployable booms assembly composed of four 1-m long bistable glass fiber tape springs was designed for the electromagnetically clean 3U CubeSat Small Explorer for Advanced Missions (SEAM). The aim of the present study was to investigate the deployment dynamics and reliability of the SEAM boom design after long-term stowage using onground experiments and simulations. A gravity offloading system (GOLS) was built and used for the onground deployment experiments. Two booms assemblies were produced and tested: a prototype and an engineering qualification model (EQM). The prototype assembly was deployed in a GOLS with small height, whereas the EQM was deployed in a GOLS with tall height to minimize the effects of the GOLS. A simple analytical model was developed to predict the deployment dynamics and to assess the effects of the GOLS and the combined effects of friction, viscoelastic relaxation, and other factors that act to decrease the deployment force. Experiments and simulations of the deployment dynamics indicate significant viscoelastic energy relaxation phenomena, which depend on the coiled radius and stowage time. In combination with friction effects, these viscoelastic effects decreased the deployment speed and the end-of-deployment shock vibrations.
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| 2. |
- Wärmefjord, Kristina, 1976, et al.
(författare)
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Form Division for Welded Aero Components in Platform-Based Development
- 2015
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Ingår i: Journal of Aerospace Engineering. - 1943-5525 .- 0893-1321. ; 28:5
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Tidskriftsartikel (refereegranskat)abstract
- In aerospace engine industry, large casted components are, because of sustainability considerations, being replaced by smaller parts that are welded together. This reduces weight because some parts can be made of lighter material. It also opens up for use of platforms. The division of a large component into smaller parts is called form division. The form division affects the geometrical robustness in the weld splitlines between the parts and thereby the weldability. By optimizing the robustness in weld splitlines, conditions for welding can be improved. A greedy algorithm for weld splitline division is described and exemplified on aerospace case studies.
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| 3. |
- Xisto, Carlos, 1984, et al.
(författare)
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Parametric Analysis of a Large-scale Cycloidal Rotor in Hovering Conditions
- 2017
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Ingår i: Journal of Aerospace Engineering. - 1943-5525 .- 0893-1321. ; 30:1, s. 04016066-04016066-14-
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Tidskriftsartikel (refereegranskat)abstract
- In this work, four key design parameters of cycloidal rotors, namely the airfoil section; the number of blades; the chord-to-radius ratio; and the pitching axis location, are addressed. The four parameters, which have a strong effect on the rotor aerodynamic efficiency are analyzed with an analytical model and a numerical approach. The numerical method is based on a finite-volume discretization of two-dimensional Unsteady Reynolds Averaged Navier-Stokes equations on a multiple sliding mesh, are proposed and validated against experimental data. A parametric analysis is then carried out considering a large-scale cyclogyro, suitable for payloads above 100 kg, in hovering conditions. Results demonstrate that the airfoil thickness significantly affects the rotor performance; such a result is partly in contrast with previous findings for small- and micro-scale configurations. Moreover, it will be shown that increasing the number of blades could result in a decrease of the rotor efficiency. The effect of chord-to-radius will demonstrate that values of around 0.5 result in higher efficiency. Finally it is found out that for these large systems, in contrast with micro-scale cyclogyros, the generated thrust increases as the pitching axis is located away from the leading edge, up to 35% of chord length. Further the shortcomings of using simplified analytical tools in the prediction of thrust and power in non-ideal flow conditions will be highlighted and discussed.
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| 4. |
- Emami, Reza, et al.
(författare)
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Quaternion-based attitude control design and hardware-in-the-loop simulation of suborbital modules with cold gas thrusters
- 2015
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Ingår i: Journal of Aerospace Engineering. - : SAGE Publications. - 0893-1321 .- 1943-5525. ; 229:4, s. 717-735
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Tidskriftsartikel (refereegranskat)abstract
- This paper discusses design and implementation of a quaternion-based attitude control system for the short-duration mission of suborbital modules using cold-gas thrusters. The quaternion-based controller generates a command torque for each channel, and a pulse-width pulse-frequency (PWPF) modulator determines the required fire signals for the thrusters. The system performance is examined through both numerical and hardware-in-the-loop simulations.
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| 5. |
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