Doctoral Degrees (Industrial Engineering)

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Browsing Doctoral Degrees (Industrial Engineering) by Subject "Aerospace industries -- Materials"

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    Qualification and certification of laser powder bed fusion for aerospace applications: a model-based production systems engineering approach.
    (Stellenbosch : Stellenbosch University, 2023-12) Gibbons, Duncan William; Van der Merwe, André Francois ; Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering. Engineering Management (MEM).
    ENGLISH ABSTRACT: Qualification approaches to aid the certification of additive manufacturing are being widely researched by academia and the aerospace industry due to the potential benefits this technology offers once industrialised. Such benefits include the ability to produce lightweight structures, reduced material waste, the ability to produce unique and complex structures, and production is economical to produce small batches when compared with some traditional manufacturing processes that are reliant on extensive tooling. However, there are challenges hindering the wider adoption of metal additive manufacturing processes in the industry. Such challenges include production controls, data management, process characterisation, material and product traceability, and a general lack of additive manufacturing qualification and certification guidance material, particularly for sub-tiered production and manufacturing organisations. This research aims at developing a production system model that defines the production system lifecycle in terms of qualification and certification, and the standard production operations for laser powder bed fusion production. This model aims at capturing the current additive manufacturing and aerospace production best practices to reduce the steep learning curve that organisations experience when implementing and industrialising new production processes such as laser powder bed fusion. A mixed-method research approach utilising both qualitative and quantitative methods was erformed. A systems engineering methodology was applied which utilised elements of design science research and model-based tools and techniques. Interviews, surveys, observations and benchmarking, and case study research methods were used during the design of conceptual production system models and during model evaluation phases. The production system model was implemented at local industrial and academic facilities. Four test cases were carried out to gather test data and evaluate the production system operation to assess the quality of the developed model. Mechanical and material testing was performed to evaluate the material and articles produced by the developed production system. The developed production system model consists of context and conceptual, operational, logical, physical, and instantiated architectural views. The model addresses production activities from an aerospace part manufacturer and producer perspective, design activities are excluded from the scope of this research. An operational architecture was modelled that defines the production system lifecycle from installation through qualification phases to ongoing production. A production system architecture was modelled that defines the standard laser powder bed fusion production operations. The production system produced material that conforms with industry specification requirements and is comparable to its wrought counterparts. An initial production run of structural components was performed to demonstrate the production system for the full product lifecycle. The use of a model-based system engineering approach for production system design improves information traceability, structuring production facilities, mapping information and material flows, controlling processes and parameters, and implementing production processes. Such aspects are important for achieving qualification and certification in the aerospace industry. Using the model, production and process controls are defined and part quality can be controlled. The developed production system model acts as a single source of truth and a mechanism for communicating production information with stakeholders. The developed architecture and model provide value as a reference for the industry for laser powder bed fusion production. The model can be used as a benchmark for future additive manufacturing and production system development undertakings and for the design and structuring of additive manufacturing quality management systems.