This thesis examines the buckling behavior of sandwich composite cylindrical shells, which are integral to the primary structure of launch vehicles. The central aim is to develop a scaling methodology based on nondimensional parameters, enabling large-scale composite structures to be scaled down to laboratory-size models while maintaining their buckling response.

The study begins with an overview of existing analytical, numerical, and experimental techniques for shell buckling analysis, alongside a review of current scaling methods in structural mechanics. Building on insights from the literature, a scaling framework is introduced by reformulating classical buckling equations in a nondimensional form. This approach allows the scaling laws to be directly derived from the equations' components but requires a comprehensive and adaptable nondimensional formulation of the structural behavior.

To establish this formulation, the work extends the nondimensional framework by first incorporating the effects of transverse shear deformations, relevant when the shells are reduced in size. Then the framework is extended to included the theoretical impact of imperfection sensitivity, tackled by incorporating a trigonometric imperfection model into the nondimensional framework.

With these extensions in place, a systematic scaling methodology is proposed. Two distinct strategies are developed: one that directly scales sandwich composite shells while preserving their structural characteristics, and another that substitutes them with equivalent composite laminate shells. While the first strategy offers greater theoretical accuracy, it is constrained by practical limitations in manufacturing scaled thicknesses. The second strategy, although more feasible for experimental implementation, introduces new complexities in ensuring equivalence between different structural configurations.

The proposed methodologies are validated through comparisons between analytical predictions, numerical simulations, and experimental results. Scaled laboratory models, produced using the more practical laminate-based strategy, show an 8% discrepancy in nondimensional buckling loads in theory compared to full-scale counterparts. However, experimental observations reveal a larger deviation of approximately 22%, underscoring the limitations of current imperfection modeling and the need for refinement in the scaling approach.

The thesis concludes by emphasizing the contributions made to nondimensional scaling methods for composite structures and highlights the importance of further experimental validation. In particular, improved modeling of imperfections and expanded laboratory testing are recommended to bridge the gap between theoretical predictions and real-world behavior. This work lays a solid foundation for the development of scaled testing protocols, advancing the design and verification of large-scale sandwich composite shell structures in aerospace applications.

The demand for pressurized, large structures in space, such as habitats or fuel deposits, is increasing as the space industry grows. The limited payload volume of launch vehicles, combined with their highly constrained shape, presents a significant challenge for these structures. Origami-inspired deployable structures have emerged as a potential solution for this problem. This work aims to design and optimize an origami-inspired deployable structure for use as a technology demonstrator in a 12U CubeSat. The choice of pattern, deployment mechanism, and material considerations are discussed as they are relevant in the initial configuration of the structural prototype. By combining two different types of printable materials, it is possible to create a pattern that is more flexible without the use of mechanical hinges. Then two different modeling methods are analyzed in order to study their physical behavior. Once all the desired configurations are computed, an optimization process is applied in order to obtain the most suitable one under the pre-defined requirements.

The TU Delft first-year aerospace engineering course, "Design and Construction," aims to bridge theoretical knowledge with practical application through challenge-based learning. Involving 400 students across 40 teams, the course integrates concepts from mechanics, materials science, and engineering drawing into realistic design projects. The first project tasks students with designing a Rocker-Bogie suspension system for a Mars rover. To enhance student engagement and understanding, a complementary activity called Mission MARIJN was introduced in the 2023-2024 academic year. Mission MARIJN includes three immersive hands-on activities: a remote-controlled 1:4 scale model of the Perseverance rover, an educational exhibit on Martian terrain, and a virtual reality experience featuring previous Mars rovers. Grounded in instructional design principles such as guided inquiry and experiential learning, these activities deepen students' grasp of design requirements and mechanical systems. Survey results from participating students indicate positive learning outcomes, with particular success in the VR and rover modelling segments. This paper presents the design, implementation, and impact of Mission MARIJN as a replicable model for enhancing engineering education through interactive, context-driven learning experiences.

Rising commercialization of the space industry has led to increasing demand for large structures in space, such as habitats and fuel tanks. However, due to the limited payload volume available, the shape of such structures is highly constrained. This calls for a structure that is flexible enough to be stowed during launch but still enough to withstand structural loads. Origami-inspired structures are an appealing design compromise as they can dynamically change their shape and volume while maintaining structural integrity. They also present the advantage of a high packaging ratio, scalability, can largely maintain their structural properties after repeated deployment, and possess flight heritage with space technology like sunshields and solar arrays. The present work aims to further the knowledge in this field by testing the viability of this concept with a deployment demonstrator fit for a 12U CubeSat mission. Two potential deployment concepts have been identified:telescopic deployment and inflation. The telescopic solution is reliable and has extensive flight heritage but adds weight and complexity to the structure. Inflation, however, is lightweight, has fewer parts, and provides a directly pressurized structure, but runs the risk of depressurization. Nevertheless, it has been used successfully to deploy origami booms and sails in space and other inflatable structures like the BEAM. Different origami patterns are selected for each of the deployment concepts. The telescopic deployment calls for the Yoshimura pattern due to its straight, non-rotational folding behaviour, and for inflation, the Kresling pattern is considered. The concepts are traded off on the basis of mission-critical criteria. After identifying a suitable origami pattern and deployment concept, a CAD model representation is created using the Rhino 3D modeling software. The model is then validated using laser-cut paper prototypes, following which it is used to identify an optimal pattern configuration that has a high usable inner volume and low packaging ratio(or folded height). Next, suitable materials and manufacturing options are traded off to identify a feasible fabrication method and materials. This is followed by a detailed description of the manufacturing process. Finally, based on the lessons learnt during the design and prototyping stages, some design guidelines are generated. Recommendations for further work are also made.

The progressive democratization of human space exploration has brought a potential demand for affordable large, pressurized structures in space such as habitats as well as fuel tanks in orbit. Unconventional space structures are a potential engineering solution because they can optimize the structural performance for the launcher's geometric limitations. Specifically, deployable origami-inspired structures allow for a compromise solution between available volume and cargo weight. Origami-inspired structures have been studied for space applications in past and recent works, but there are still gaps between the in-orbit requirements and technological challenges with the current state-of-the-art. Consequently, there is a need for small scale demonstrators for this technology that will allow to characterize and validate the deployment concept. Such a small-scale demonstrator would fit within 12U CubeSat (or equivalent small sat configurations) and would unveil possible technical challenges not considered in the modelling stage. This work explores the design of a prototype for a deployable structure with a high packaging potential and a small number of degrees of freedom. A cylindrical origami deployable structure is studied under its processes of folding and deployment. This configuration has also the advantage of a possible pressure-controlled deployment, one with special interest for habitable modules or, additionally, fuel tanks for transportation and storage. In particular, the first steps towards a complete design of the demonstrator are explored: the shape optimization, the material selection, and its structural behaviour. To design this demonstrator a parametric trade-off study of the different origami patterns is performed: looking for an optimal packaging ratio. Once the geometrically optimal configurations are obtained for each origami pattern, relevant materials are selected, and possible manufacturing challenges are discussed.

This paper presents the derivation of nondimensional buckling equations of sandwich cylindrical shells made of composite facesheets with a shear deformable core. The procedure yields an analytical solution in terms of a series of nondimensional parameters for the axial buckling load investigating the influence of the core transverse shear. The developed equations and the nondimensional parameters are used to study the buckling response of different shells, and the calculated buckling loads are compared to the buckling values obtained by neglecting the transverse shear. Graphs and tables are presented to show the effects of the nondimensional parameters on the nondimensional buckling load. The results are verified by finite element analyses using the commercial code Abaqus.

Studying buckling behavior of large shell structures through full-scale test articles can be complex and expensive. Therefore, reduced-scale structures are often preferred for investigating buckling behavior. However, designing reduced-scale structures that are representative of the full-scale structure can be difficult. An analytical scaling methodology for compression-loaded sandwich composite cylindrical shells based on the nondimensionalization of the buckling equations is presented herein. The methodology was used to develop scaled configurations that show similar buckling responses to the full-scale baseline configuration. Finite element analysis results showed that both a baseline and a scaled configuration buckled similarly, when the nondimensional stiffness, defined as the ratio between the nondimensional load and nondimensional displacement, was matched between the different scale models. Limitations of the methodology are discussed and are believed to be a result of neglecting the flexural anisotropy and the transverse shear compliance. A preliminary material failure assessment for the different scales is also considered.

The study of the buckling behavior of large shell structures through full-size tests can be complex and expensive. Therefore, scaled structures are often preferred to investigate the buckling behavior efficiently. However, it can be difficult to design scaled structures that are representative of the full-scale structures. Herein, an analytical scaling methodology for compression-loaded sandwich composite cylinders based on the nondimensionalization of the buckling equations is presented. The methodology is used to develop scaled configurations that show a similar buckling response. Both the baseline and the scaled configurations are verified by finite-element analysis. Limitations of the methodology are discussed and are a result of neglecting the flexural anisotropy and the transverse shear compliance.