The student Egoitz Aldanondo Beguiristain obtained an OUTSTANDING CUM LAUDE qualification
The student Egoitz Aldanondo Beguiristain obtained an OUTSTANDING CUM LAUDE qualification
The student Egoitz Aldanondo Beguiristain obtained an OUTSTANDING CUM LAUDE qualification
Thesis title: Friction Stir Welding technology for advanced manufacturing of aircraft structures
Court:
- Chairmanship: Dulce Maria Esteves Rodrigues (Universidade de Coimbra)
- Vocal: Juana Valer Goñi (Aernnova Engineering Division)
- Vocal: Maria San Sebastian Ormazabal (Lortek)
- Vocal: Gurutze Arruebarrena Lizarralde (Mondragon Unibertsitatea)
- Secretary: Gorka Plata Redondo (Mondragon Unibertsitatea)
Abstract:
One of the current challenges in the aeronautic sector is the reduction of fuel consumption aiming at energy efficiency, reduction of emissions as well as reductions in operational costs of the aircraft. In order to face this challenge, increasingly lighter structures are required for more efficient and environmental-friendly airframe systems.
From the manufacturing process point of view, Friction Stir Welding (FSW) is an innovative joining technology with potential to substitute the traditionally used riveting for aircraft structure manufacturing. From the material point of view, the development of Third-Generation aluminium-lithium alloys have created opportunities for the introduction of low density and high-performance aluminium alloys. The successful implementation of both innovations, i.e., FSW technology and Third-Generation aluminium-lithium alloys opens new perspectives for the development of advanced aircraft structures. However, it is necessary to develop appropriate FSW process conditions in order to maximize the quality of the joints and structures that comply with the stringent requirements of the aeronautic sector.
This thesis is mainly focused on the FSW process development for its implementation in the integral reinforced panel manufacturing characterised by stringer-skin type joints using Third-Generation aluminium-lithium alloys. Although several alloys of this type have been investigated, the work is mainly focused on the AA2060-T8E30 and AA2099-T83 alloys. Critical factors for FSW process development such as tool designs, welding parameters and effects introduced by innovative corrosion protection techniques (Cr-free surface treatments, sealants) are investigated. The impact of all these factors in the quality of FSW joints is investigated by metallographic examination and mechanical tests including optical and electron microscopy, static pull-out, static tensile and fatigue tests. As a result of the work, optimized FSW process conditions are defined including an alternative FSW tool design capable to produce high-quality FSW joints for overlap joint configurations.
The thesis has been developed in the framework of the project ecoTECH, which is a core-partner project of the Clean Sky 2 initiative for research and development of new technologies for future aircraft. An excellent collaborative work has been carried out among project partners and the development of innovative fuselage panel demonstrators is in progress at the time when this thesis is being deposited. The conclusions obtained in the thesis are being applied to the FSW manufacturing of the fuselage demonstrators with the aim of increasing the TRL level of this type of advanced structures. This could permit to introduce FSW as an enabling technology for the advanced manufacturing of aircraft structures showing benefits such as weight savings, reduction of energy consumption, reduction in the manufacturing time and costs, as well as advances towards a more automatic and digital manufacturing.
In order to present the work in the clearest way possible, the thesis mentions 11 articles presented in a chronological way that represent the work performed in the FSW technology development for different types of aluminium alloys and overlap joint configurations. The contributions of each article are explained in each corresponding chapter. Nevertheless, the core articles that led to the completion of this thesis are articles 9, 10 and 11. These are the relevant articles that comply with the academic requirements and must be considered as a compendium of publications in substitution of the traditional PhD dissertation.