Airport surface movement operations present a promising opportunity for enhancing airport sustainability, as up to 25% of airport emissions originate from taxiing aircraft. This study explores the use of Electric Towing Vehicles (ETVs) to tow aircraft to runways, eliminating the operational use of aircraft engines during taxiing. Given the high cost of ETVs, their effective deployment is essential. This research adopts a Multi-Agent Pickup and Delivery (MAPD) framework to optimize ETV operations, addressing both the task assignment and path planning aspects of this problem. A novel task assignment method based on Ant Colony Optimization (ACO) is proposed, capable of efficiently scheduling towing and charging tasks for ETVs. The proposed method outperforms benchmark Mixed Integer Linear Programming (MILP) methods in terms of runtime and scalability, while delivering a competitive solution quality. The ACO-based task assignment method is integrated with a state-of-the-art motion planning algorithm based on Priority Based Search (PBS) and Safe Interval Motion Planning (SIMP). The resulting MAPD solution method is evaluated through its application in a high-fidelity simulation of Amsterdam Airport Schiphol (AAS). The simulation results indicate that deploying 22 ETVs at AAS can achieve a 57% reduction in the annual addressable CO2 emissions, while ensuring the economic feasibility of the operational concept.

In developing Type V hydrogen tanks for energy storage and propulsion in commercial airliners, the key design criterion is maintaining tightness under cryogenic conditions. A concern is that anomalies in the laminate could cause microcracks which compromise the tightness. This study examined how resin flow, caused by an expanding mould during curing, creates a gradient in the local fibre volume fraction (FVF) across the laminate. The impact of resin system selection, autoclave cycle parameters, mandrel material, and fibre tension on the FVF gradient was investigated. Cylindrical specimens were manufactured in a process replicating automated fibre placement (AFP), with a piezoelectric sensor measuring contact pressure at the mandrel-laminate interface during the autoclave cycle as an indicator of resin flow and FVF spread. Significant correlations were found between resin flow and all parameters except fibre tension. The resin's viscosity profile and gelation characteristics had the most substantial impact on the FVF spread. Resins with high viscosity and short gelation times lowered the FVF spreads the most. Mandrel materials with lower thermal expansion coefficients (CTE) also reduced FVF gradients, though to a lesser extent. Adjusting the autoclave cycle to lower temperatures for longer periods resulted in the least significant reduction in FVF spread; however, this approach holds high potential for further improvement if more data on resin rheology and cure kinetics are available to optimise the autoclave cycle. These findings provide valuable insights for minimising FVF gradients in the design of carbon fibre-reinforced polymer (CFRP) tanks for liquid hydrogen.

Pushing the envelope of aerospace structures requires the complete exploitation of their potential in terms of load-carrying capacity per unit weight for both economic and ecological reasons: the two most important being the reduction of fuel consumption and greenhouse gas emissions. A key approach involves allowing structures like stiffened panels to function within the post-buckling range domain while in service. To do so, the finite element approach allows a broad design space for researching the post-buckling behaviour of such structures.

Accurately representing post-buckling behaviour in finite element models requires accounting for geometric and loading imperfections. The present study explores their effects on the post-buckling behaviour of a composite L-stiffened panel. A finite element model is created and validated based on an experimental case. This is then further modified to incorporate imperfections. Geometric imperfections are modelled using linear eigenvalue modes, while loading imperfections are introduced via a rigid loading plate making contact at an angle.

The research showed that both first and higher eigenmode combinations for geometric imperfections influence post-buckling behaviour. Their shape and amplitude impact the transition into post-buckling and their ultimate loads. Similar behaviour was also observed for loading imperfections. Additionally, their configuration also showed an offset in axial displacement results. These insights emphasise the need for precise imperfection modelling to promote safer and more efficient post-buckling design of aerospace structures.

Fibre-reinforced laminated composites are constructed layer-by-layer, allowing their material properties to be easily tailored relative to their isotropic counterparts (metallic alloys). Moreover, a composite structure with variable stiffness (VS) can be made by spatially tailoring stiffness across a laminate. This permits better load distribution within a structure, efficiently using a given material, and allow for lighter construction. Typically, the design of VS structures follows a bi-level procedure: first, the structure’s stiffness distribution is optimised using lamination parameters (LPs), and second, the stacking sequences (SS) of differently oriented fibres are designed to achieve the desired stiffness distribution. However, the designs envisioned using LPs are only sometimes exactly matched by the designed SS. The shortcomings faced during this conversion are called the ’Inverse Problem’. Upon reviewing the existing techniques in literature to handle the inverse problem, it was understood that converting LPs into SS is challenging without incurring substantial computational costs or imposing significant restrictions on allowable fibre orientations in the design. Such restrictions tend to under-utilise the directional properties of the fibres. Thus, there was a need to explore and develop better stiffness design methods for laminated composites by bridging the gap between LPs and SS in a computationally efficient way.

In response to this challenge, a hierarchical design framework was proposed to handle the Inverse Problem. Diverging from conventional methods that directly design the SS and try to match a given set of LPs, this framework divides the problem into two distinct stages. Initially, the focus is to use the In-Plane LPs and determine the number of layers in each orientation within a laminate, also called the Fibre Angle Distribution (FAD). Subsequently, the FAD serves as an interim solution, and the SS can be designed by using the Out-of-Plane LPs along with it. This problem partitioning enhances computational efficiency and offers potential benefits in solving the Inverse Problem more effectively. Given the time constraints inherent to a master thesis, the primary undertaking of this study was to efficiently design the FAD while accommodating a wide range of possible fibre orientations. To address this, a novel method using the Fast-Fourier Transform (FFT) was developed to facilitate FAD design with ply angle multiples of 15° (or [∆15° ] = [0, ±15, ±30, ±45, ±60, ±75, 90]). Moreover, empirical guidelines for SS design, such as the Symmetry and Balancing rule, were incorporated into the design step.

The primary contribution of this report is introducing an FFT-based method to design FADs, a novel addition to the existing body of research. Upon extensive testing, it was shown that this implementation could convert LPs into multiple unique FAD solutions in less than 0.3 seconds on a regular office laptop, outperforming other methods in literature by at least ten times. Furthermore, the implementation was also used to demonstrate the benefits of designing laminated composites using [∆15°] over the conventional [∆45°] orientations (or [0, ±45, 90]). In light of the positive results, it is pointed out that the In-Plane LPs (and consequently the In-Plane stiffness) are known to be sensitive only to the FAD and not their SS. As such, the readers of this thesis are presented with a very computationally efficient approach for designing laminated composites for In-Plane Stiffness...

The final report focused on the detailed design of the final chosen concept, which is a BWB aircraft with a distributed propulsion system powered by liquid hydrogen. Before doing the actual technical design part, a market analysis is made to investigate the future demand for this type of aircraft. To do so, the SWOT analysis, market characteristics, and competitor analysis are made. After that, an estimation of the market dynamics & trends, as well as the expected demand for the aircraft is made. In financial analysis, the financial forecast and strategies for the whole aircraft program are discussed, from which the unit cost, operational cost, return on investment and cost-breakdown structure can be found. The report concludes that the Lightning2 program is a promising step towards more sustainable aviation. It emphasizes the need for further development and adaptation to technological advancements to maintain a competitive position in the market​