Design for Producibility in Fabricated Aerospace Components - A framework for predicting and controlling geometrical variation and weld quality defects during multidisciplinary design
Doktorsavhandling, 2020

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.

Quality Assurance



Design for Producibility

Welding simulation

Variation Management

Design for Manufacturing

robust design

On site at Virtual Development Laboratory (VDL), Chalmers University of Technology and Online via ZOOM Password 195859
Opponent: Professor Fredrik Elgh, Jönköping University, Sweden


Julia Madrid

Chalmers, Industri- och materialvetenskap, Produktutveckling

A Welding Capability Assessment Method (WCAM) to support multidisciplinary design of aircraft structures

International Journal on Interactive Design and Manufacturing,; Vol. 12(2018)p. 833-851

Artikel i vetenskaplig tidskrift

Madrid, J., Andersson, P., Söderberg, R., Wärmefjord, K., Kveselys, D., Lindkvist, L. and Lööf, J. Automated and interactive evaluation of welding producibility in an MDO environment for aircraft components.

In the aerospace industry, a nominal product geometry can be designed to deliver optimal aerodynamic and structural performance. However, when we fabricate this product, the product is afflicted with geometrical variation and other kinds of quality problems. Thus, at the end of the fabrication process we might obtain a product which it is not what we intended. In this type of industry, manufacturing quality problems can cause costly and time-consuming repairs and redesign loops.

Until now, the evaluation of the effect that design concepts has on producibility criteria in the case of welded highly integrated performance aerospace components had relied to a great extent on expert judgement and physical testing. However, if the objective is to analyze a large number of geometrical design variants, this approach may become costly. The consequence is that integrated products are first evaluated and optimized towards performance, thus leaving producibility assessments in second place.

Thus, the key questions with which to assess producibility during the design process of highly integrated performance products that are welded are: Can we produce this design and at what quality level and cost?

The thesis results support designers at assessing producibility by predicting virtually and rapidly the welding quality of a large number of product design variants during the multidisciplinary design space process of fabricated aerospace components.

The research presented in this thesis has focused on producibility problems for the particular case of welded components in highly integrated performance applications. This research has aimed at contributing an understanding, as well as, providing support in the form of a framework, methods and tools to the field of Quality Engineering in general and Quality-Geometry Assurance and Variation Management in particular.


Produktionsteknik, arbetsvetenskap och ergonomi

Rymd- och flygteknik

Bearbetnings-, yt- och fogningsteknik





Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4851


Chalmers tekniska högskola

On site at Virtual Development Laboratory (VDL), Chalmers University of Technology and Online via ZOOM Password 195859


Opponent: Professor Fredrik Elgh, Jönköping University, Sweden

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