Design techniques to support aircraft systems development in a collaborative MDO environment

The aircraft design is a complex multidisciplinary and collaborative process. Thousands of disciplinary experts with different design competences are involved within the whole development process. The design disciplines are often in contrast with each other, as their objectives might be not coincident, entailing compromises for the determination of the global optimal solution. Therefore, Multidisciplinary Design and Optimization (MDO) algorithms are being developed to mathematically overcome the divergences among the design disciplines. However, a MDO formulation might identify an optimal solution, but it could be not sufficient to ensure the success of a project. The success of a new project depends on two factors. The first one is relative to the aeronautical product, which has to be compliant with all the capabilities actually demanded by the stakeholders. Furthermore, a “better” airplane may be developed in accordance with customer expectations concerning better performance, lower operating costs and fewer emissions. The second important factor refers to the competitiveness among the new designed product and all the other competitors. The Time-To-Market should be reduced to introduce in the market an innovative product earlier than the other aeronautical industries. Furthermore, development costs should be decreased to maximize profits or to sell the product at a lower price. Finally, the development process must reduce all the risks due to wrong design choices. These two main motivations entail two main objectives of the current dissertation. The first main objective regards the assessment and development of design techniques for the integration of the aircraft subsystems conceptual design discipline within a collaborative and multidisciplinary development methodology. This methodology shall meet all the necessities required to design an optimal and competitive product. The second goal is relative to the employment of the proposed design methodology for the initial development of innovative solutions. As the design process is multidisciplinary, this thesis is focused on the on-board systems discipline, without neglecting the interactions among this discipline with all the other design disciplines. Thus, two kinds of subsystems are treated in the current dissertation. The former deals with hybrid-electric propulsion systems installed aboard Remotely Piloted Aerial Systems (RPASs) and general aviation airplanes. The second case study is centered on More and All Electric on-board system architectures, which are characterized by the removal of the hydraulic and/or pneumatic power generation systems in favor of an enhancement of the electrical system. The proposed design methodology is based on a Systems Engineering approach, according to which all the customer needs and required system functionalities are defined since the earliest phase of the design. The methodology is a five-step process in which several techniques are implemented for the development of a successful product. In Step 1, the design case and the requirements are defined. A Model Based Systems Engineering (MBSE) approach is adopted for the derivation and development of all the functionalities effectively required by all the involved stakeholders. All the design disciplines required in the MDO problem are then collected in Step 2. In particular, all the relations among these disciplines – in terms of inputs/outputs – are outlined, in order to facilitate their connection and the setup of the design workflow. As the present thesis is mainly focused on the on-board system design discipline, several algorithms for the preliminary sizing of conventional and innovative subsystems (included the hybrid propulsion system) are presented. In the third step, an MDO problem is outlined, determining objectives, constraints and design variables. Some design problems are analyzed in the present thesis: un-converged and converged Multidisciplinary Design Analysis (MDA), Design Of Experiments (DOE), optimization. In this regard, a new multi-objective optimization method based on the Fuzzy Logic has been developed during the doctoral research. This proposed process would define the “best” aircraft solution negotiating and relaxing some constraints and requirements characterized by a little worth from the user perspective. In Step 4, the formulation of the MDO problem is then transposed into a MDO framework. Two kinds of design frameworks are here considered. The first one is centered on the subsystems design, with the aim of preliminarily highlighting the impacts of this discipline on the entire Overall Aircraft Design (OAD) process and vice-versa. The second framework is distributed, as many disciplinary experts are involved within the design process. In this case, the level of fidelity of the several disciplinary modules is higher than the first framework, but the effort needed to setup the entire workflow is much higher. The proposed methodology ends with the investigation of the design space through the implemented framework, eventually selecting the solution of the design problem (Step 5). The capability of the proposed methodology and design techniques is demonstrated by means of four application cases. The first case study refers to the initial definition of the physical architecture of a hybrid propulsion system based on a set of needs and capabilities demanded by the customer. The second application study is focused on the preliminary sizing of a hybrid-electric propulsion system to be installed on a retrofit version of a well-known general aviation aircraft. In the third case study, the two kinds of MDO framework previously introduced are employed to design conventional, More Electric and All Electric subsystem architectures for a 90-passenger regional jet. The last case study aims at minimizing the aircraft development costs. A Design-To-Cost approach is adopted for the design of a hybrid propulsion system

Preliminary Sub-Systems Design Integrated in a Multidisciplinary Design Optimization Framework

The aircraft design is a complex subject since several and completely different design disciplines are involved in the project. Many efforts are made to harmonize and optimize the design trying to combine all disciplines together at the same level of detail. Within the ongoing AGILE (Horizon 2020) research, an aircraft MDO (Multidisciplinary Design Optimization) process is setting up connecting several design tools and competences together. Each tool covers a different design discipline such as aerodynamics, structure, propulsion and systems. This paper focuses on the integration of the sub-system design discipline with the others in order to obtain a complete and optimized aircraft preliminary design. All design parameters used to integrate the sub-system branch with the others are discussed as for their redefinition within the different detail level of the design

Technologies for Enabling System Architecture Optimization

Optimization of complex system architectures can support the non-biased search for novel architectures in the early design phase. Four aspects needed to enable architecture optimization and the author's views on how to solve them are discussed: formalization of the architecture design space, systematic exploration of the design space, conversion from architecture model to simulation model, and flexible simulation of architecture performance. Modeling the design space is done using the Architecture Design Space Graph (ADSG) implemented in ADORE. Systematic exploration can be done using evolutionary or surrogate-based optimization algorithms. Architecture to simulation model conversion can be done using an object-oriented approach using class factories, or using theMultiLinQ tool to synchronize a central data repository. Finally, simulation environments should expose a flexible and modular interface to be used in architecture optimization. A jet engine architecting problem is presented that demonstrates various aspects of system architecture optimization

Integration of on-board systems preliminary design discipline within a collaborative 3rd generation MDO framework

The integration of the on-board systems design discipline in a collaborative Multidisciplinary Design and Optimization (MDO) framework is presented in this paper. The collaborative MDO framework developed within the context of the EU funded H2020 AGILE project is selected as reference. The technologies developed or made available in the context of the AGILE project are employed for the integration within the MDO framework of ASTRID, an on-board systems design tool owned by Politecnico di Torino. The connection of the tool with a common namespace (i.e. CPACS) and its implementation within two Process Integration and Design Optimization (PIDO) environments are described. An application study is eventually presented, showing the benefits and the potentialities of the integration of the on-board systems design discipline within a collaborative MDO framework

The Influence of Architectural Design Decisions on the Formulation of MDAO Problems

Formulating system architecture design problems as optimization problems has the potential to help reduce bias in searching the combinatorial design space, and help find novel system architectures to better meet the challenges of the future. Typical types of design decisions present in architecture optimization problems, however, pose some special challenges to currently existing MDO problem formulations. Design variables are mixed-discrete, a hierarchy might exist between design variables where one design variable can deactivate another, and there might be multiple conflicting objectives to optimize for simultaneously. This poster explores some of the impacts these effects can have on MDO problems, in particular regarding the inclusion or exclusion of analysis blocks

High efficiency regional aircraft conceptual design and on-board systems preliminary study

A conceptual design of a new regional plane has been performed, investigating the application of the three lifting surfaces configuration and laminar fuselage on a larger aircraft. On-board systems have subsequently been sized and their installation validated in a CAD model. Finally, a flight simulation has been executed comparing the new design against a traditional regional aircraft, demonstrating its potential benefit on fuel consumption

From System Architecting to System Design and Optimization: A Link Between MBSE and MDAO

Optimization of system architectures can help deal with finding better system architectures in a large design space plagued by combinatorial explosion of alternatives. To enable architecture optimization, the design space should therefore be formalized into a numerical optimization problem, and it should be possible to quantitatively evaluate architecture alternatives. This paper presents a methodology for generating and modeling architecture design spaces using the Architecture Design Space Graph (ADSG), and using collaborative Multidisciplinary Design Analysis and Optimization (MDAO) techniques to evaluate architectures. Collaborative MDAO leverages disciplinary expertise while ensuring that analysis tools exchange data consistently and correctly using a central data schema. The problem solved in this paper is the missing link between architecture optimization and collaborative MDAO: the reflection of generated architectures in the central data schema. It is solved by the authors by mapping architecture components and Quantities of Interest (QOIs) to the central data schema using Data Schema Operations (DSOs). Such a mapping also assists the user in identifying missing or unnecessary disciplinary analysis tools. Three web-based software tools implementing the methodology are presented. Finally, the methodology and tools are demonstrated using the design of a supersonic business jet as an example

An MBSE Architectural Framework for the Agile Definition of System Stakeholders, Needs and Requirements

Model Based Systems Engineering (MBSE) approaches are rapidly spreading among organizations and industries due to all their claimed benefits over traditional document-based approaches. Benefits include for instance enhanced design quality of systems, clearer development of system requirements and specifications and improved communications within the design teams. Currently, MBSE methods and tools are mainly employed to successfully develop complex systems, such as aircraft or its components. However, this paper proposes to adopt MBSE also in the design of development systems, which aim to design complex systems. In particular, this paper focuses on the first activities of a typical Systems Engineering Product Development process: identification of system stakeholders, collection of their needs and development of system requirements. The main outcome delivered from this paper is an architectural framework, i.e. a guideline for the modeling of complex systems. More specifically, the architectural framework is still under development, and hence the current version focuses on the modeling of stakeholders, needs and requirements of complex systems. The focus of the proposed architectural framework is on the agility for the definition phases of complex systems. In other words, it is developed to streamline, improve and accelerate the definition and modeling of complex systems. Details of the architectural framework including the means to represent all the system information are provided. In addition, the architectural framework for the development of complex systems is supported by an MBSE development system, currently being addressed in the EU-funded research project AGILE 4.0. The MBSE development system is presented in this paper together with an example of its application for the definition of complex systems: an horizontal tail plane for a regional jet aircraft, designed and manufactured within an aeronautical supply chain consisting of different companies

Macroinvertebrate as indicators of acidification in high altitude alpine lakes

No abstract availableCinque laghi svizzeri vengono presi come esempio per valutare il recupero dall\u27acidificazione evidenziato per gli aspetti chimici a partire dalla met? degli anni \u2790, ma i metodi per la valutazione del livello di acidit? basati sui macroinvertebrati sono stati sviluppati in Nord Europa e su corsi d\u27acqua e quindi sembra poco credibile poterli utilizzare per acque lacustri. Questo contributo vuole quindi evidenziare quali fra le metriche applicate, e generalmente in uso a livello europeo, riflette meglio le variazioni di acidit? presenti nei diversi laghi classificati come sensibili (2 laghi), con bassa alcalinit? (2), e alcalini (1). I laghi e i loro emissari vengono presentati sulla base delle loro caratteristiche chimiche e faunistiche secondo i principali gruppi di interesse ai fini di una loro classificazione. Le metriche applicate sono raccolte in due gruppi: metriche generali (abbondanze relative per i diversi gruppi, ecc) e metriche specifiche (diversi indici). Le metriche vengono applicate in due diverse tipologie di ambienti, acque ferme e acque correnti appartenenti ai medesimi laghi. Dai risultati si rileva che lungo il litorale solo poche metriche fra quelle scelte danno indicazioni di differenze faunistiche correlate ai diversi livelli di acidificazione raggiunti dai laghi, mentre nelle acque correnti sono molte di pi? le metriche applicabili, perch? molte delle specie prese in considerazione dalle metriche sono specifiche di questi ambienti e non si trovano nelle acque ferme dove altri fattori, pi? importanti, determinano le differenze di popolamento fra un lago ed un altro. Concludendo si pu? affermare che: i macroinvertebrati d\u27acqua corrente sono migliori indicatori di acidit?, l\u27identificazione tassonomica a livello di specie di chironomidi ed oligocheti ? utile per migliorare la valutazione del livello di acidit? di ambienti d\u27alta quota

Integration of on-board Systems preliminary design discipline within a collaborative 3rd Generation MDO framework

The integration of the on-board systems design discipline in a collaborative Multidisciplinary Design and Optimization (MDO) framework is presented in this paper. The collaborative MDO framework developed within the context of the EU funded H2020 AGILE project is selected as reference. The technologies developed or made available in the context of the AGILE project are employed for the integration within the MDO framework of ASTRID, an on-board Systems design tool owned by Politecnico di Torino. The connection of the tool with a common namespace (i.e. CPACS) and its implementation within two Process Integration and Design Optimization (PIDO) environments are described. An application study is eventually presented, showing the benefits and the potentialities of the integration of the on-board systems design discipline within a collaborative MDO framework