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Proposed in this thesis is a methodology to enable yacht designers to develop innovative structural concepts, even when the loads experienced by the yacht are highly uncertain, and has been implemented in sufficient detail to confirm the feasibility of this new approach. The new approach is required because today??s yachts are generally lighter, getting larger and going faster. The question arises as to how far the design envelope can be pushed with the highly uncertain loads experienced by the structure? What are the effects of this uncertainty and what trade-offs in the structural design will best meet the overall design objectives? The new approach provides yacht designers with a means of developing innovative structural solutions that accommodate high levels of uncertainty, but still focus on best meeting design objectives constrained by trade-offs in weight, safety and cost. The designer??s preferences have a large, and not always intuitive, influence on the necessary design trade-offs. This in turn invites research into ways to formally integrate decision algorithms into knowledge-based design systems. A lean and robust design system has been achieved by developing a set of tools which are blanketed by a fuzzy decision algorithm. The underlying tool set includes costing, material optimisation and safety analysis. Central to this is the innovative way in which the system allows non-discrete variables to be utilized along with new subjective measures of structural reliability based on load path algorithms and topological (shape) optimisation. The originality in this work is the development of a knowledge-based framework and methodology that uses a fuzzy decision making tool to navigate through a design space and address trade-offs between high level objectives when faced with limited design detail and uncertainty. In so doing, this work introduces the use of topological optimisation and load path theory to the structural design of yachts as a means of overcoming the historical focus of knowledge-based systems and to ensure that innovative solutions can still evolve. A sensitivity analysis is also presented which can quantify a design??s robustness in a system that focuses on a global approach to the measurement of objectives such as cost, weight and safety. Results from the application of this system show new and innovative structural solutions evolving that take into account the designers preferences regarding cost, weight and safety while accommodating uncertain parameters such as the loading experienced by the hull.

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The present Ph.D. thesis addresses the problem of knowledge-based engineering template update in product design. The reuse of design knowledge has become a key asset for the company's competitiveness. Knowledge-based engineering templates allow to store best practices and knowhow via formulas, rules, scripts, etc. This design knowledge can then be reused by instantiating the template. The instantiation results in the creation of an instance of the template in the specified context. In the scope of complex and large products, such as cars or aircrafts, the maintenance of knowledge-based engineering templates is a challenging task. Several engineers from various disciplines work together and make evolve the templates in order to extend their capabilities or to fix bugs. Furthermore, in some cases, the modifications applied to templates should be forwarded to their instances in order that they benefit from the changes. These issues slow down the adoption of template technologies at a large scale within companies. The objective of this work is to propose an approach in order to support engineers in the template update related tasks. In order to address these issues, a process supporting the template update related tasks is defined. Then a framework is proposed that helps design engineers during the template update process by providing a decision support system and a strategy for the update of template instances. The former is a system designed to ease the collaboration between various experts in order to solve template related problems. The latter aims at providing a sequence of updates to follow, in order to forward the templates' modifications to their instances. This sequence is computed with data extracted from models and templates, which are stored in an ontology designed for this purpose. The ontology is used to represent and to infer knowledge about templates, products and their relations. This facilitates the construction of update sequences as it provides an efficient overview of relationships, even implicit ones.

Intensive competition on the global market puts great pressure on manufacturing companies to develop and produce products that meet requirements from customers and investors. One key factor in meeting these requirements is the efficiency of the product development and the production preparation processes. Design automation is a powerful tool to increase efficiency in these two processes. The benefits of automating the manufacturability analysis process, a part of the production preparation process, are shortened lead-time, improved product performance, quality assurance, and, ultimately, decreased costs. Further, automation is beneficial as it increases the ability to adapt products to new product specifications with production preparations done in a few or in a single step. During the automation process, knowledge about the manufacturability analysis process is collected and stored in central systems, thus allowing full control over the design of production equipments. Topics addressed in this thesis include the flexibility of design automation systems, knowledge-bases containing alternative design rules, the automation of the finite element analysis process, manufacturability analysis over several productions steps, and the determination of production limits by looping the automated manufacturability analysis process. These topics are discussed in connection with the rotary draw bending of aluminum profiles. It is concluded that the concept of design automation can be applied to the manufacturability analysis process at different levels of automation depending on the characteristics of the implemented knowledge. The concept of object orientation should be adapted when implementing a knowledge-base and when developing the geometrical representations of the products. This makes a design automation system flexible enough to edit underlying knowledge and to extend the targeted design space. It is possible to automate the process of setting up, running, and interpreting finite element analyses to a great extent, enabling the design automation system to evaluate its own design proposals. It is also possible to enable such systems to consider sequences of manufacturing steps and loop them to develop decision support guiding engineers early in the design process, saving time and money while still assuring high product quality.

Proposed in this thesis is a methodology to enable yacht designers to develop innovative structural concepts, even when the loads experienced by the yacht are highly uncertain, and has been implemented in sufficient detail to confirm the feasibility of this new approach. The new approach is required because today??s yachts are generally lighter, getting larger and going faster. The question arises as to how far the design envelope can be pushed with the highly uncertain loads experienced by the structure? What are the effects of this uncertainty and what trade-offs in the structural design will best meet the overall design objectives? The new approach provides yacht designers with a means of developing innovative structural solutions that accommodate high levels of uncertainty, but still focus on best meeting design objectives constrained by trade-offs in weight, safety and cost. The designer??s preferences have a large, and not always intuitive, influence on the necessary design trade-offs. This in turn invites research into ways to formally integrate decision algorithms into knowledge-based design systems. A lean and robust design system has been achieved by developing a set of tools which are blanketed by a fuzzy decision algorithm. The underlying tool set includes costing, material optimisation and safety analysis. Central to this is the innovative way in which the system allows non-discrete variables to be utilized along with new subjective measures of structural reliability based on load path algorithms and topological (shape) optimisation. The originality in this work is the development of a knowledge-based framework and methodology that uses a fuzzy decision making tool to navigate through a design space and address trade-offs between high level objectives when faced with limited design detail and uncertainty. In so doing, this work introduces the use of topological optimisation and load path theory to the structural design of yachts as a means of overcoming the historical focus of knowledge-based systems and to ensure that innovative solutions can still evolve. A sensitivity analysis is also presented which can quantify a design??s robustness in a system that focuses on a global approach to the measurement of objectives such as cost, weight and safety. Results from the application of this system show new and innovative structural solutions evolving that take into account the designers preferences regarding cost, weight and safety while accommodating uncertain parameters such as the loading experienced by the hull.

Saab Aeronautics’ section Overall Design and Survivability develops early aircraft concepts and utilizes Computer Aided Design (CAD) to ensure the feasibility of principal- and critical characteristics. Saab has over the years developed several start models of aircrafts in CAD from pre-defined aircraft configurations, which are to some extent non-generic. When new configurations are to be explored, manual- and repetitive work is required if the new configuration cannot be attained solely through parametric modifications of a start model. The complexity of these CAD models also demands great knowledge of how aircraft components interact with each other to ensure compatibility. The project covered in this thesis was thus carried out to develop a more effective way for Saab to create and explore a larger design space. This by creating a framework that consists of a product configurator coupled with a library of generic CAD models. The product configurator that was created is the Saab Tradespace Analyzer & Reconfigurator (STAR), which takes compatibility relationships into consideration to facilitate concept selection. The STAR also provides a dynamic design space calculation to indicate how close the user is to a final concept selection. Two generic CAD models were created, a fuselage model and an air inlet model. A skeleton model was also created in order to reduce model dependencies and to control the main geometry of the aircraft product. In addition to these, an already existing wing model was implemented to form the library of generic CAD models. The framework coupling the STAR with the CAD library utilizes design automation to allow automatic CAD model generation of a concept that has been selected within the STAR. It was concluded through extrapolation that the created framework would allow Saab to create and explore a larger design space in a more effective way than what is done today, provided the library of CAD models were to contain the same number of components as today’s start models.

When working with complex aircraft design it is necessary to be able test configurations easily. At Saab this is done in several ways. When looking at the weapons integration on the Gripen Aircraft, clearance analysis (called feasibility studies at Saab) are created to evaluate if new external stores can be mounted. This is done manually in CATIA by measuring and evaluating the result. To ease the work when performing these repetitive tasks, it is possible to take advantage of Knowledge Based Engineering, KBE. This thesis revolves around implementing KBE in the process. The approach is to create a configurator that can handle the different external stores and perform the required tasks. The end result is a configurator with a Graphical User Interface, GUI, in which the user gets help with the feasibility study and which requires light manual input from the user. The configurator performs the study and produces a Word report for the user to examine. The resulting time saving is around 75 to 80 percent from the original process. The conclusion is that the configurator can facilitate the feasibility studies at Saab by reducing the time and lower the threshold for the user. Even though the process is not fully automated, the configurator is judged to perform at a satisfying degree.

The pace of development in aviation technology is increasing, and there is a constantneed for new concepts to keep up. An innovative concept is desired to reach the netzero emission and sustainability target visualized in Flight path 2050. Introducing digital models and virtualization into aviation fields reduces time consumption onmanual modelling and increases design accuracy. Digital mock-up models also helpin minimizing costs due to errors in the later stage of development or manufacturing. The Institute of Systems Architecture in Aeronautics at German AerospaceCenter (DLR) works in digitizing cabin design environments with extensive implementation of the Knowledge-Based Engineering (KBE) approach. The virtual cabindesign system tool also known as Fuselage Geometry Assembler (FUGA) providesa digital model of the cabin of both single and twin aisle configurations of commercial aircraft. The information of aircraft characteristics is provided to FUGA using Common Parametric Aircraft Configuration Schema (CPACS). CPACS coupled with FUGA provides the user with a consistent model of aircraft and cabindesign, when viewed through a virtual platform provides an immersive experienceto be inside an aircraft cabin before physical production. The multidisciplinary capability of FUGA provides experts from different disciplines to perform analysis such as vibration analysis on the cabin environment. For ease of usage and better visualization of information from FUGA, a web-based application through Flask is hosted for FUGA. This enables the user to access the FUGA tool without the needof installing the tool on their devices. With the world now moving towards a greener approach, an alternative propulsion system may require a different fuel tank configuration. Retro-fit of liquid hydrogen fuel tank into an existing aircraft’s fuselage is done using FUGA tool and aircraft performance analysis is conducted and the outcomes are studied. The enhanced and advanced model of twin-aisle configuration, now on par with single-aisle configuration is used for hydrogen tank sensitivity analysis. The comparative study of different aisle configurations retro-fitted with liquidhydrogen fuel tank is further conducted for arriving at an optimal design point fora balance in range and passenger capacity.

Examensarbetet som detaljeras i denna rapport är utfört på uppdrag av företaget Xperdi AB, designautomationsexperter vars önskemål med projektet var en demonstration av effekten avdesignautomation. Projektförslaget innefattar utveckling och användningen av ett automationsramverk för automatisk generering av unika hydraulcylindermodeller efter specifika designkrav. För att genomföra arbetet har olika verktyg och metoder kombinerats. Modellens delkomponenter konstruerades i CAD-programmet SolidWorks och kompletterades med nödvändiga data för att förbereda CAD-filerna för konfiguration. XCC (Xperdi CAD Configurator) är ett konfigurationsverktyg som hanterar datan från CAD och erbjuder extern styrning och konfiguration av CAD-modellen. För att automatisera konfigurationen som möjliggörs av XCC har ett gränssnitt för designval och olika verkställande operationer skapats i programmet Visual Studio, med tillhörande kod skriven i det objektorienterade språket Visual Basic. Koden i Visual Studio kommunicerar med XCC och innehåller konfigurativa instruktioner för modellen baserat på valda inputs, men även direkt med SolidWorks för verkställandet av specifika SolidWorks-funktioner. Projektet har resulterat i en anpassningsbar hydraulcylindermodell vars specifikationer styrs från gränssnittet, med funktionalitet för automatisk generering av hålbilder och ritningar för samtliga unika konfigurationer i designrymden. Även tidsvinsterna av designautomation har undersökts. Resultaten indikerar att arbetet med att upprätta ett automationsramverk har betydande fördelar, dels med avseende på hastigheten av designändringar som uppmätts, dels med avseende på mervärdet som tillkommer vid reduktion av repetitivt arbete. Dock tas i beaktning att fördelarna av designautomation bör vägas mot resursinvesteringarna som krävs. / The thesis detailed in this report was carried out on behalf of the company Xperdi AB, designautomation experts whose goal for the project was to demonstrate the effectiveness of designautomation. The project proposal includes development and use of an automation framework for automatic generation of unique hydraulic cylinder models based on specific design requirements. To execute the work, various tools and methods were combined. The model's subcomponents were constructed in the CAD program SolidWorks and supplemented with the necessary data to prepare the CAD files for configuration. XCC (Xperdi CAD Configurator) is a configuration tool that manages data from CAD and offers external control and configuration of the CAD model. To automate the configuration enabled by XCC, an interface for design choices and various executive operations was created in the Visual Studio program, with accompanying code written in the object-oriented language Visual Basic. The code in Visual Studio communicates with XCC and contains configurative instructions for the model based on selected inputs, as well as directly with SolidWorks to perform specific SolidWorks functions. The project has resulted in an adaptive hydraulic cylinder model whose specifications are controlled from the interface, with functionality for automatic generation of hole patterns and drawings for all unique configurations in the design space. The time savings of design automation have also been examined. The results indicate that the work of establishing an automation framework has significant benefits, both in terms of the speed of design changes measured and the added value that comes from reducing repetitive work. However, it should be noted that the benefits of design automation should be weighed against the resource investments required.