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

A multimodal approach to product presentations

AbstractMultimodality approaches discourse focusing on the analysis of the semiotic modes that help fulfil the communicative purpose of a particular genre, which in the case of product presentations is to persuade of the excellence of the product. We argue that a Multimodal Discourse Analysis approach is especially suitable for the study of product presentations since persuasion in this genre implies the use of different semiotic modes (Chaiken & Eagly, 1976; Poggi & Pelachaud, 2008). The aim of this paper is to present a methodological approach to the study of product presentations from a MDA perspective along with potential pedagogical implications

Multimodal enactment of characters in conference presentations

In academic oral genres such as conference presentations, speakers resort to more than words to convey meaning. Research also suggests that persuasion, an important element of the communicative purpose of conference presentations, is frequently achieved through a combination of semiotic modes. Therefore, a skilful orchestration of these modes can be considered key to achieving effective communication in this genre. However, our understanding of persuasion has often focused on specific elements of the message considered in isolation and mainly from the linguistic perspective. Relatively little attention has been paid to the overall persuasive effect achieved by the complex multimodal ensemble. This study approaches the analysis of persuasive strategies in conference presentations combining multimodal discourse analysis and ethnographic methods. It focuses on a particular attention-getting technique: enactment of characters, or acting the part of a person that is being referred to. Our analysis shows how it is achieved through the orchestration of different modes such as words, intonation, gestures, head movements, gaze and facial expression

Design For Manufacturing and Producibility in Fabricated Aerospace Structures

Aircraft component suppliers must adopt new design strategies in order to absorb market growth and become more competitive at the same time as they satisfy environmental demands. To deal with this situation, weight reduction has been the key to success and have made jet engines more fuel efficient. A strategy already adopted by some engine suppliers to reduce weight has been fabrication in which small cast or forged parts are welded together into a final shape. Besides increasing the number of forming suppliers which reduces cost, another main advantage of fabrication is the 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 investigate and propose methods and tools within Design and Quality Engineering to solve producibility problems involving welded high performance structures. The research group “Robust Design and Geometry Assurance” 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 with regard to various disciplines. However, as studied in this thesis, existing methods and tools 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 produce process capability data that can be reused in future projects.To fulfill that need, this thesis presents a producibility model to represent the fabrication process in order to understand how variation is originated and propagated. With this representation at hand, this thesis builds on the Welding Capability Assessment Method (WCAM). The WCAM is tool with which to support systematic identification and assessment of design issues related to product geometry critical to the welding process. Within this method, a list of potential failure modes during welding is connected to specific design parameters. Once the critical design parameters have been identified, quantitative methods are proposed to calculate tolerances to reduce the likelihood of welding failures.Combinations of specialized information about welding problems, know-how, inspection and simulation data have been used to evaluate the welding capabilities of a number of product geometries. Patterns and engineering rules can be extracted by combining sources of data, both qualitative and quantitative. With WCAM, evaluations are no longer limited to a single geometry and the study of the process parameter window. Instead, the welding capability space, meaning all geometrical variants that fulfill manufacturing quality, is assessed. This information can be used to perform optimization and evaluate trade-off alternatives in terms of producibility during design space exploration and analysis, thus supporting the multidisciplinary design process

Robust design of aero engine structures: Transferring form error data when mapping out design spaces for new turbine components

In aerospace modeling and simulation, nominal geometries are norm. However, it has been shown that form error, or irregular deviations in geometry, aggravates thermal stresses, which in turn reduces product life. While form error can be measured on manufactured products using 3D laser scanners, a simulation infrastructure is needed to analyze its effects on aerodynamic, structural and thermal performance. Moreover, in early product development phases, before manufacturing has begun, form error data is not available. This paper describes a method for including form error data in mainstream simulation activities. The suggested method works by creating parametric CAD-models to accommodate form error. There are two main benefits of this method. Firstly, it enables proactive robustness simulations where substantial design changes can be tested and evaluated. Secondly, it enables the mapping of data from previous products onto new designs, which means that robustness analyses can be performed in earlier design phases. To demonstrate this capability, a case study shows how a robust optimization scheme using genetic algorithms can improve product robustness to form error. The results show that form error have effects of the same order of magnitude as key design parameter changes. This finding underlines the importance of performing form error analyses in exploratory early design phases

Dynamic platform modeling for concurrent product-production reconfiguration

To meet a wide range of customer needs, a variety of product concepts can be modeled employing a platform approach. Whereas frequent market changes can be accommodated by dynamically modifying product concepts in iterations, capabilities in production are seldom well incorporated as part of design iterations. In this paper, a dynamic platform modeling approach that supports concurrent product-production reconfiguration is presented. The approach builds on Set-Based Concurrent Engineering (SBCE) processes and a function modeling technique is used to represent product-production variety streams inherent in a production operation model. To demonstrate the approach, a comprehensive case from the aerospace industry is presented. Conceptual representations of a set of aero engine sub-systems and a variety of welding configurations, including their inherent constraints, are mutually modeled and assessed. The results show that a set of product-production alternatives can be dynamically controlled by integrating product-production constraints using a production operation model. Following SBCE processes, inferior alternatives can be put aside until new information becomes available and a new set of alternatives can be reconfigured. The dynamics and concurrency of the approach can potentially reduce the risk of late and costly modifications that propagate from design to production

ECG-Based Unsupervised Clustering in Coronary Artery Disease Associates with Ventricular Arrhythmia

Coronary Artery Disease (CAD) is a leading cause of life-threatening ventricular arrhythmias (LTVAs). This study aimed to identify distinct clusters of CAD individuals based on QRS morphology using a 3-nearest neighbors clustering algorithm. Cluster 1, characterized by the lowest QRS amplitudes and widest QRS complexes, was strongly associated with LTVA risk

“Ein weites Feld”: revisiting the Political and Republican Kant

El escrito continúa una discusión mantenida por Macarena Marey, María Julia Bertomeu y Nuria Sánchez Madrid en torno a la capacidad de los principios del republicanismo kantiano para transformar el espacio social en un ámbito en el que la autosuficiencia material constituya una de las condiciones fundamentales para que la igualdad formal ante la ley y la libertad política puedan actualizarse. En estas coordenadas se manifiestan también algunas discrepancias en lo concerniente a la percepción kantiana de las injusticias sociales y políticas propias de su tiempo, si bien se alcanza el acuerdo de que el diseño institucional del republicanismo kantiano constituye un dispositivo conceptual suficiente para eliminar la desigualdad económica que comporta pasividad civil y política.This paper engages in a discussion held by Macarena Marey, María Julia Bertomeu and Nuria Sánchez Madrid on the capacity of Kant's republicanism to transform the social realm in a space where material self-sufficiency acts as a key condition to embody formal equality towards the law and political freedom. In this discussion the authors also show some disagreements concerning Kant's perception of social and political injustice of his time, although they agree in the thesis that the institutional agenda contained in Kantian republicanism means a sound conceptual framework for removing the economic inequality that leads to civil and political passivity.Fil: Bertomeu, Maria Julia. Centro de Investigaciones Filosóficas. Instituto de Filosofía "Ezequiel de Olaso" - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Filosofía "Ezequiel de Olaso"; ArgentinaFil: Sánchez Madrid, Nuria. Universidad Complutense de Madrid; Españ