| 1. |
- Amadori, Kristian, 1976-, et al.
(författare)
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Aircraft Conceptual Design Optimization
- 2008
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Ingår i: International Congress of the Aeronautical Sciences ICAS,2008. - Stockholm, Sweden : ICAS.
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Konferensbidrag (refereegranskat)abstract
- Aircraft design is an inherently multidisciplinary activity that requires different models and tools for various aspects of the design. At Linköping University a novel design framework is being developed to support the initial conceptual design phase of new aircraft. By linking together various modules via a userfriendly spreadsheet interface, the framework allows multidisciplinary analysis and optimizations to be carried out. The geometrical model created with a high-end CAD system, contains all the available information on the product and thus it plays a central role in the framework. In this work great attention has been paid to techniques that allow creating robust yet highly flexible CAD models. Two different case studies are presented. The first one is a hypothetic wing-box design that is studied with respect to aerodynamic efficiency and loads, and to structural analysis. In this study two approaches were compared. In one case the wing-box design was optimized with a fixed number of structural elements, where only dimensions and position were allowed to change. Then the same wing-box was analyzed allowing also the number of structural elements to vary. Thus only the parts that are required are left and a more efficient design can be obtained. In the second case study a mission simulation is performed on a UAV-type aircraft. Required data for the simulation are gathered from the CAD model and from aerodynamic analysis carried out with PANAIR, a high order panel code. The obtained data are then used as inputs parameters for flight simulation in order to determined hydraulic systems characteristics.
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| 2. |
- Amadori, Kristian, 1976-, et al.
(författare)
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Using CAD-Tools and Aerodynamic Codes in a Distributed Conceptual Design Framework
- 2007
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Ingår i: Aerospace Sciences Meeting and Exhibit,2007. - USA : AIAA.
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Konferensbidrag (refereegranskat)abstract
- Aircraft design is an inherently multi-disciplinary activity that requires different models and tools for various aspects of the design. At Linköping University a novel design framework is being developed to support the initial conceptual design phase of a new aircraft. Different modules are included, each one addressed to analyze and evaluate different aspects of the airplane, such as its aerodynamics, its weight and structure, its sub systems and its performances. All modules are easily accessible from a user-friendly interface based on an Excel spreadsheet. The link between all modules is based on Service Oriented Architecture (SOA) and allows both distribution and integration of all functions. This paper will present the framework, give an overview of its development status and give an indication on the future work.
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| 6. |
- Axin, Mikael, 1984-, et al.
(författare)
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A Flexible Working Hydraulic System for Mobile Machines
- 2016
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Ingår i: International Journal of Fluid Power. - : Taylor & Francis. - 1439-9776 .- 2332-1180. ; 17:2, s. 79-89
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This paper proposes a novel working hydraulic system architecture for mobile machines. Load sensing, flow control and open-centre are merged into a generalized system description. The proposed system is configurable and the operator can realize the characteristics of any of the standard systems without compromising energy efficiency. This can be done non-discretely on-the-fly. One electrically controlled variable displacement pump supplies the system and conventional closed-centre spool valves are used. The pump control strategies are explained in detail. Experimental results demonstrate one solution to the flow matching problem and the static and dynamic differences between different control modes.
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| 7. |
- Axin, Mikael, 1984-, et al.
(författare)
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A Hybrid of Pressure and Flow Control in Mobile Hydraulic Systems
- 2014
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Ingår i: 9th InternationalFluid Power Conference (IFK). Vol. 1. Aachen, Germany, 24-26 March 2014. - 9783981648003 ; , s. 190-201
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Konferensbidrag (refereegranskat)abstract
- This paper presents a hybrid pump controller approach for mobile hydraulic systems, influenced by both pressure and flow. The controller is tuneable to be able to set the order of importance of the pressure and flow controller, respectively. It is thus possible to realize a load sensing system, a flow control system or a mix of the two. Using a low load pressure feedback gain and a high flow control gain, a system emerges with high energy efficiency, fast system response, high stability margins and no flow matching issues. In this paper, both theoretical studies and practical implementations demonstrate the capability of a hybrid pump control approach.
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| 8. |
- Axin, Mikael, 1984-, et al.
(författare)
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Design Rules for High Damping in Mobile Hydraulic Systems
- 2013
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Ingår i: 13th Scandinavian International Conference on Fluid Power. - : Linköping University Electronic Press. - 9789175195728 ; , s. 13-20
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Konferensbidrag (refereegranskat)abstract
- This paper analyses the damping in pressure compensated closed centre mobile working hydraulic systems. Both rotational and linear loads are covered and the analysis applies to any type of pump controller. Only the outlet orifice in the directional valve will provide damping to a pressure compensated system. Design rules are proposed for how the system should be dimensioned in order to obtain a high damping. The volumes on each side of the load have a high impact on the damping. In case of a small volume on the inlet side, the damping becomes low. However, the most important thing is to design the outlet orifice area properly. There exists an optimal orifice dimension for maximized damping; both smaller and larger orifice areas give lower damping independently of the volumes. This paper presents a method to dimension the outlet orifice area and the load volumes in order to obtain a desired system damping. Experimental results, which confirm the theoretical expectations, are also presented. The conclusions are that it is possible to obtain a high damping contribution from the outlet orifice if the system is dimensioned correctly. However, the energy efficiency needs to be considered while improving the damping
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| 9. |
- Axin, Mikael, 1984-, et al.
(författare)
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Dynamic Analysis of Single Pump, Flow Controlled Mobile Systems
- 2011
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Ingår i: The Twelfth Scandinavian International Conference on Fluid Power, SICFP'11. - 9789521525193 ; , s. 223-238
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Konferensbidrag (refereegranskat)abstract
- Interest has increased in flow controlled systems in the field of mobile fluid power. The capital distinction between traditional load-sensing (LS) systems and flow controlled systems is that the pump is controlled based on the operator’s total flow demand rather than maintaining a certain pressure margin over the maximum load pressure. One of the main advantages of flow controlled systems is the absence of the feedback of the highest load pressure to the pump controller. In this paper, a dynamic analysis is performed where flow controlled and LS systems are compared. It is shown how instability can occur in LS systems due to the pump controller and proven that no such instability properties are present in flow controlled systems. A drawback with one type of flow controlled system is that the highest load dynamically will disturb the lighter loads. This paper shows a novel way to optimize the damping in such systems by controlling the opening position of the directional valve independently of the flow. The mentioned disturbance between the highest load to the others can thereby be reduced.
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| 10. |
- Axin, Mikael, 1984-, et al.
(författare)
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Energy Efficient Fluid Power System for Mobile Machines with Open-centre Characteristics
- 2014
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Ingår i: 9th JFPS International Symposium on Fluid Power. Matsue, Japan, 28-31 October 2014. - : The Japan Fluid Power System Society. - 4931070108 ; , s. 452-459
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents a flexible and energy efficient system solution which mimics the behaviour of an open-centre system. An electro-hydraulic variable displacement pump and closed-centre valves are used. Instead of having a flow in the open-centre gallery, that flow is calculated using a pressure sensor and a valve model. The variable pump is then controlled in order to only deliver the flow that would go to the actual loads. It is also possible for the operator to decide how much load dependency there should be. The extreme case is not having any load dependency at all, resulting in a system where the pump displacement setting is controlled according to the sum of all requested load flows. It is thus possible to realize a system design with open-centre characteristics, a flow control system or something in between. Each operator can thereby get their optimal control characteristic while having high energy efficiency.
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