Design space exploration of a jet engine component using a combined object model for function and geometry

The design of aircraft and engine components hinges on the use of computer aided design (CAD) models and the subsequent geometry-based analyses for evaluation of the quality of a concept. However, the generation (and variation) of CAD models to include radical or novel design solutions is a resource intense modelling effort. While approaches to automate the generation and variation of CAD models exist, they neglect the capture and representation of the product’s design rationale—what the product is supposed to do. The design space exploration approach Function and Geometry Exploration (FGE) aims to support the exploration of more functionally and geometrically different product concepts under consideration of not only geometrical, but also teleological aspects. The FGE approach has been presented and verified in a previous presentation. However, in order to contribute to engineering design practice, a design method needs to be validated through application in industrial practice. Hence, this publication reports from a study where the FGE approach has been applied by a design team of a Swedish aerospace manufacturers in a conceptual product development project. Conceptually different alternatives were identified in order to meet the expected functionality of a guide vane (GV). The FGE was introduced and applied in a series of workshops. Data was collected through participatory observation in the design teams by the researchers, as well as interviews and questionnaires. The results reveal the potential of the FGE approach as a design support to: (1) Represent and capture the design rationale and the design space; (2) capture, integrate and model novel solutions; and (3) provide support for the embodiment of novel concepts that would otherwise remain unexplored. In conclusion, the FGE method supports designers to articulate and link the design rationale, including functional requirements and alternative solutions, to geometrical features of the product concepts. The method supports the exploration of alternative solutions as well as functions. However, scalability and robustness of the generated CAD models remain subject to further research

Enabling parametric design space exploration by non-designers

In mass customization, software configurators enable novice end-users to design customized products and services according to their needs and preferences. However, traditional configurators hardly provide an engaging experience while avoiding the burden of choice. We propose a Design Participation Model to facilitate navigating the design space, based on two modules. Modeler enables designers to create customizable designs as parametric models, and Navigator subsequently permits novice end-users to explore these designs. While most parametric designs support direct manipulation of low-level features, we propose interpolation features to give customers more flexibility. In this paper, we focus on the implementation of such interpolation features into Navigator and its user interface. To assess our approach, we designed and performed user experiments to test and compare Modeler and Navigator, thus providing insights for further developments of our approach. Our results suggest that barycentric interpolation between qualitative parameters provides a more easily understandable interface that empowers novice customers to explore the design space expeditiously

A Virtual Design of Experiments Method to Evaluate the Effect of Design and Welding Parameters on Weld Quality in Aerospace Applications

During multidisciplinary design of welded aircraft components, designs are principallyoptimized upon component performance, employing well-established modelling and simulationtechniques. On the contrary, because of the complexity of modelling welding process phenomena,much of the welding experimentation relies on physical testing, which means\ua0 welding producibility aspects are considered after the design has already been established. In\ua0 addition, welding optimization research mainly focuses on welding process parameters, overlooking the potential impact of product design. As a consequence, redesign loops and welding rework increases product cost. To solve these problems, in this article, a novel method that combines the benefits of design of experiments (DOE) techniques with welding simulation is presented. The aim of the virtual design of experiments method is to model and optimize the effect of design and welding parameters interactions early in the design process. The method is explained through a case study, in which weld bead penetration and distortionare quality responses to optimize. First, a small number of physical welds are conducted to develop and tune the welding simulation. From this activity, a new combined heat source model is presented.Thereafter, the DOE technique optimal design is employed to design an experimental matrix that enables the conjointly incorporation of design and welding parameters. Welding simulations are then run and a response function is obtained. With virtual experiments, a large number of design and welding parameter combinations can be tested in a short time. In conclusion, the creation of a meta-model allows for performing welding producibility optimization and robustness analyses during early design phases of aircraft component

Towards automated conceptual design space exploration

In\ua0mature and safety-concerned industries, such as the aerospace industry, product development is often incremental and design solutions are limited to improvements of an existing design. Radical changes to the known product architecture are avoided, for reasons of reliability, lack of technology or lack of design space exploration (DSE) methods. This thesis aims to investigate into the challenges for DSE, and how it can be improved to be faster, wider and more systematic. This research has been undertaken in four different research projects, addressing the challenges of the aerospace industry. The process of exploring the design space, the set of all possible designs, can be divided into three phases: to define the design space boundaries, to populate this design space with concepts, and lastly, to analyse the different concepts to find the one which provides the highest value. A deficiency in the description of functions and constraints which constitute the design space dimensions and boundaries, rooted in the lack of methods, has been identified to reduce the available search space already in the beginning. To populate this search space, developers need to generate representations of their new designs. These representations, commonly 3D geometries in the form of CAD models, are too rigid in the form they are used today. Therefore, it is expensive to create many variants, which differ in solutions and shape. This reduces the design space population to only a few concepts, derived from the legacy design. The analysis of alternative concepts is challenged through different maturities and variety of concepts.The coverage of multiple hierarchical search spaces, from geometry over solutions to value, has been identified as a driver for wider DSE. Furthermore, the need for a product development approach that is capable to bridge the levels of modelling abstraction. Enhanced Function-Means (EF-M) modelling, a function model applied in all studies referenced in this thesis, bridges the abstraction from a verbal description to a teleological graph, while enabling a more systematic capture of the design space boundaries. However, a subsequent gap towards geometry models could be observed in all studies. This hindered a faster design space exploration, since extensive manual labour is required to bridge these abstraction levels. For further work, the closing of the abstraction gap in the product modelling methods is seen as the primary goal for further work, either by extending the already applied function- and geometry modelling methods, or by including other frameworks

Design for Producibility in Fabricated Aerospace Components - A framework for predicting and controlling geometrical variation and weld quality defects during multidisciplinary design

In the aerospace industry, weight reduction has been one of the key factors in making aircraft more fuel efficient in order to satisfy environmental demands and increase competitiveness. One strategy adopted by aircraft component suppliers to reduce weight has been fabrication, in which small cast or forged parts are welded together into a final shape. Fabrication increases design freedom due to the possibility of configuring several materials and geometries, which broadens out the design space and allows multioptimization in product weight, performance quality and cost. However, with fabrication, the number of assembly steps and the complexity of the manufacturing process have increased. The use of welding has brought to the forefront important producibility problems related to geometrical variation and weld quality.The goal of this research is to analyze the current situation in industry and academia and propose methods and tools within Engineering Design and Quality Engineering to solve producibility problems involving welded high performance integrated components. The research group “Geometry Assurance and Robust Design” at Chalmers University of Technology, in which this thesis has been produced, has the objective to simulate and foresee geometrical quality problems during the early phases of the product realization process to allow the development of robust concepts and the optimization of tolerances, thus solving producibility problems. Virtual manufacturing is a key within the multidisciplinary design process of aerospace components, in which automated processes analyze broad sets of design variants to trade-off requirements among various disciplines. However, as studied in this thesis, existing methods and tools to analyze producibility do not cover all aspects that define the quality of welded structures. Furthermore, to this day, not all phenomena related to welding can be virtually modelled. Understanding causes and effects still relies on expert judgements and physical experimentation to a great deal. However, when it comes to assessing the capability of many geometrical variants, such an effort might be costly. This deficiency indicates the need for virtual assessment methods and systematic experimentation to analyze the producibility of the design variants and produce process capability data that can be reused in future projects.To fulfill that need, this thesis provides support to designers in assessing producibility by virtually and rapidly predicting the welding quality of a large number of product design variants during the multidisciplinary design space process of fabricated aerospace components.The first step has been to map the fabrication process during which producibility problems might potentially occur. The producibility conceptual model has been proposed to represent the fabrication process in order to understand how variation is originated and propagated. With this representation at hand, a number of methods have been developed and employed to provide support to: 1) Identify and 2) Measure what affects producibility; 3) Analyze the effect of the interaction between factors that affect producibility and 4)Predict producibility. These activities and methods constitute the core of the proposed Design for Producibility framework. This framework combines specialized information about welding problems (know-hows), and inspection, testing and simulation data to systematically predict and evaluate the welding producibility of a set of product design variants. Through this thesis, producibility evaluations are no longer limited to a single geometry and the study of the process parameter window. Instead, a set of geometrical variants within the design space can be analyzed. The results can be used to perform optimization and evaluate trade-offs among different disciplines during design space exploration and analysis, thus supporting the multidisciplinary design process of fabricated (welded) aerospace components

Continuous Open Access Special Issue "Aircraft Design": Number 2/2020

Following the successful initial Special Issue on “Aircraft Design (SI-1/2017)”, this is already the second SI “Aircraft Design (SI-2/2020)”. Activities in the past showed that aircraft design may be a field too small to justify its own (subscription-based) journal. A continuous open access special issue may fill the gap. As such, the Special Issue “Aircraft Design” can be a home for all those working in the field who regret the absence of an aircraft design journal. SI-2/2020 contains seven papers; an Editorial: 1.) "Publishing in 'Aircraft Design' with a Continuous Open Access Special Issue" and six Original Research Articles about 2.) Amphibious Aircraft Developments, 3.) Design Space Exploration of Jet Engine Components, 4.) Study of Subsonic Wing Flutter, 5.) Design Optimization of a Blended Wing Body Aircraft, 6.) Discrete Mobile Control Surfaces, 7.) Electro-Impulse De-Icing Systems

Systematic Design Space Exploration of Dynamic Dataflow Programs for Multi-core Platforms

The limitations of clock frequency and power dissipation of deep sub-micron CMOS technology have led to the development of massively parallel computing platforms. They consist of dozens or hundreds of processing units and offer a high degree of parallelism. Taking advantage of that parallelism and transforming it into high program performances requires the usage of appropriate parallel programming models and paradigms. Currently, a common practice is to develop parallel applications using methods evolving directly from sequential programming models. However, they lack the abstractions to properly express the concurrency of the processes. An alternative approach is to implement dataflow applications, where the algorithms are described in terms of streams and operators thus their parallelism is directly exposed. Since algorithms are described in an abstract way, they can be easily ported to different types of platforms. Several dataflow models of computation (MoCs) have been formalized so far. They differ in terms of their expressiveness (ability to handle dynamic behavior) and complexity of analysis. So far, most of the research efforts have focused on the simpler cases of static dataflow MoCs, where many analyses are possible at compile-time and several optimization problems are greatly simplified. At the same time, for the most expressive and the most difficult to analyze dynamic dataflow (DDF), there is still a dearth of tools supporting a systematic and automated analysis minimizing the programming efforts of the designer. The objective of this Thesis is to provide a complete framework to analyze, evaluate and refactor DDF applications expressed using the RVC-CAL language. The methodology relies on a systematic design space exploration (DSE) examining different design alternatives in order to optimize the chosen objective function while satisfying the constraints. The research contributions start from a rigorous DSE problem formulation. This provides a basis for the definition of a complete and novel analysis methodology enabling systematic performance improvements of DDF applications. Different stages of the methodology include exploration heuristics, performance estimation and identification of refactoring directions. All of the stages are implemented as appropriate software tools. The contributions are substantiated by several experiments performed with complex dynamic applications on different types of physical platforms

On the military utility of spectral design in signature management : a systems approach

There is an ongoing duel between military sensor development and developments in signature management. The last decade, with warfare characterized by joint expeditionary operations and asymmetry, has favored sensors. However, on account of the worsening security situation in Europe, there is now also an increasing interest in efforts to increase survivability of own military platforms. Spectral design is one of several promising technologies with extensive research potentially suitable for Low Observable platforms. It involves creating desired spectral optical responses from surfaces, in this case reducing contrast to background, by choosing suitable materials and structures. The challenge to a military decision-maker, faced with inherent uncertainties concerning the future and with limited resources, is how to choose among alternative capabilities, technologies or equipment. Correspondingly, on account of the system character of the signature attribute, researchers in technologies for signature management has difficulties communicating relevant basis for these decisions. The scope of this thesis is therefore to find and analyze patterns in decision situations involving technology or technical systems for military use, and the purpose is to propose conceptual and methodological contributions to support future decisionmaking. The technology focus is on spectral design and the application in focus is signature management of Low Observable military platforms. The research objective is addressed from a military system and capability centric perspective using methods from several disciplines in the military sciences domain. The result is synthesized from four separate studies: 1) on spectral design using systematic review of literature, 2) on military utility using a concept formation method, 3) on modeling for how to operationalize a link between spectral design and measures of military utility using methods of military operations research, and, 4) on cases of systems engineering of military Low Observable platform designs. In summary, the result of the work presented in this thesis is a compilation of related work in military sciences, systems engineering and material optics into a framework to support effective decision-making in relevant contexts. The major contribution to theory is a proposed concept called Military Utility, capturing how to communicate the utility of technical systems, or technology, in a military context. It is a compound measure of Military Effectiveness, Military Suitability and Affordability. Other contributions can be expected to support decision-making in practice; - the so-called Ladder-model is a template for how to quantitatively operationalize the military effectiveness dimension of Military Utility regarding the use of spectral design; - an applied Ladder-model is demonstrated, useful for analyzing the military utility of spectral designs in Low Observable attack aircraft; - a probabilistic framework for survivability assessments is adopted into a methodology for doing the analysis, and lastly; - a generic workflow is identified, from relevant development programs, including decision-situations that can benefit from the adopted methodology.Det finns en ständigt pågående kamp mellan militär sensorutveckling och signaturanpassning. Det senaste decenniet, som karaktäriserats av asymmetrisk krigföring och gemensamma expeditionära operationer, har gynnat sensorerna. Nu har emellertid intresset för effektivare skydd av egna militära plattformar ökat till följd av den försämrade säkerhetssituationen i Europa. Spektral design är då en av flera lovande teknologier med potential att användas vid signaturanpassning och det bedrivs en omfattande forskning. Teknologin kan sägas omfatta tekniker för att skapa en yta med de optiska egenskaper som önskas. I den tillämpning som studeras i den här avhandlingen är syftet att minska ett objekts kontrast till bakgrunden, d.v.s. dess signatur, och det sker genom lämpligt val av ytors material och struktur. Militära beslutsfattare står ofta inför en stor utmaning då de ska välja mellan framtida förmågor, teknologier eller utrustning. Sådana beslutssituationer präglas ofta av stor osäkerhet och en begränsad ekonomi. Sett från det andra hållet är det ofta svårt för forskare inom teknologier för signaturanpassning att kommunicera relevant beslutsunderlag, på grund av signaturers speciella systemkaraktär. Avhandlingen omfattar en undersökning med syftet att finna och analysera eventuella mönster i beslutssituationer rörande teknologier eller tekniska system för militär användning. Målet är att lämna konceptuella och metodmässiga bidrag till stöd för framtida beslutsfattning. Teknologin i fokus är spektral design och tillämpningen är signaturanpassning av militära plattformar. Forskningsfrågan adresseras från ett militärt förmågecentrerat systemperspektiv med metoder från flera discipliner inom militärvetenskapen. Resultatet har sammanställts från fyra separata studier: 1) av spektral design med hjälp av systematisk granskning av tidigare forskning, 2) av militär nytta med hjälp av en metod för konceptformering, 3) av modelleringen av en länk mellan spektral design och mått på militär nytta med hjälp av militär operationsanalys, och, 4) av design av smyganpassade plattformar med hjälp av fallstudier. Resultatet från studierna bildar sammantaget med relaterad tidigare forskning från militärvetenskap, systemteknik och materialoptik ett ramverk till stöd för effektivare beslutsfattning. Det främsta bidraget till teoribildningen utgörs av ett förslag till koncept kallat militär nytta. Konceptet fångar hur nyttan med tekniska system, eller teknologier, bör kommuniceras i militära sammanhang. Militär nytta är här ett sammanvägt mått bestående av militär effektivitet, av militär lämplighet och av överkomlighet. Andra bidrag förväntas stödja beslutsfattning direkt i praktiken; - den s.k. stegmodellen kan användas som mall vid kvantifiering av den militära effektivitetsdimensionen vid värdering av den militära nyttan med spektral design; - användningen av stegmodellen har demonstrerats i fallet med smyganpassade attackflygplan; - ett sannolikhetsbaserat ramverk för överlevnadsuppskattningar har anpassats att användas som analysmetod, och till sist; - ett generiskt arbetsflöde med relevanta beslutssituationer där analysmetoden kan komma till nytta har identifierats genom studier av tidigare utvecklingsprojekt