The thesis addresses a relevant and technically demanding topic related to the structural design and verification of the CIMER CubeSat mission. The author successfully developed a CAD model, prepared a mass budget, and conducted vibration analyses using FEM methods. The work demonstrates a solid understanding of engineering tools and the practical constraints associated with CubeSat development. The connection to the ESA Fly Your Satellite! programme further increases the practical significance of the project. Nevertheless, while the thesis achieves the stated objectives at a functional level, several aspects limit its overall quality from an academic perspective. The literature review is overly generic and provides only a broad introduction to CubeSat systems, FEM methods, and ECSS standards. Greater emphasis on the current state of research in spacecraft structural analysis, recent CubeSat structural verification studies, and comparable missions would have strengthened the scientific foundation of the work. The thesis relies heavily on standards and engineering documentation but contains relatively limited engagement with scientific literature and research findings.

From a methodological perspective, the work is primarily simulation-based and lacks experimental validation. The FEM analyses are generally well executed; however, the discussion of modelling assumptions, mesh sensitivity and numerical uncertainties could be more rigorous. Several conclusions rely on engineering judgement rather than systematic verification. Additionally, compliance with ESA and ECSS requirements is discussed, but a comprehensive verification and traceability framework is not fully demonstrated. The thesis reads more as an engineering design report than a research-oriented master's thesis, with limited critical analysis of alternative design approaches or deeper scientific investigation. While the project clearly satisfies the essential technical objectives and represents a valuable contribution to the CIMER mission, the limited depth of literature review, absence of validation testing, and relatively modest scientific contribution reduce its academic impact. Overall, the thesis can be considered a competent and successful engineering project, but one that falls short of excellence in terms of research depth and critical analysis. Points proposed by supervisor: 74

The thesis addresses the structural design and finite element verification of a CubeSat platform, including modal, quasi-static, vibration, and pressure vessel analyses. The topic is highly relevant to small satellite development and demonstrates a good amount of engineering effort. The work is generally well structured, and the author shows familiarity with finite element methods, ECSS standards, and spacecraft structural design principles.

The theoretical background gives a great overview of general CubeSat design in all aspects. However, sections such as the electrical power system, attitude and orbit control system, on-board data handling, and communication are not directly relevant to the main goal of this thesis. Although these topics are relevant to a complete CubeSat, shortening these sections would make the theoretical background more focused. The identification of the main standards required for design verification is well presented. The author clearly states which sources are used in determining compliance with the requirements that need to be met. At this point, it would be helpful to provide a summary of all required analyses needed to verify the design and the threshold values for each evaluation criterion.

One of the goals of this thesis is to design the main structure of the CubeSat, so I would assume there was some iterative process that led to the final design. However, the final version of the design is presented at the beginning, which is a little unfortunate. If the student went through the full design process, it would be beneficial to show it in the thesis. All components and the overall structure are well described, including their mounting features. In the design of the pressure vessel, a simplification to a 1/8 model without the final features is made, which is sufficient for the intended purpose. It is somewhat confusing that the final design does not use external radii on the vessel, while the FEM analysis includes outer radii along each edge. The selection of the radius and wall thickness could also be described in more detail. Variations with radii of 5 mm and 10 mm and wall thicknesses of 1 mm and 2 mm are evaluated, but in the end a design with a 3 mm radius and 3 mm wall thickness is simulated and selected without any variation study using these dimensions. In this case, the Response Surface Optimization toolbox in Ansys would be very helpful. One aspect not considered in this analysis is the weight of the pressure vessel, which should also be evaluated. Regarding the sealing concept, a C-ring is selected, and it would be helpful to provide an analysis of the fastener preload to verify the required sealing pressure.

The mass budget analysis is performed in accordance with the requirements and is well documented, including all margins. The complete FEM model is described very well. The tables describing materials, material properties, elements, and connections are helpful and presented in a clear and readable form. As for meshing, the methods used are described, but the overall text remains quite general. Here I would expect the author to state the element sizes and mesh quality parameters that are important for the numerical solution. One important part that is missing is mesh convergence validation. From the figures showing the mesh, it appears sufficiently refined to provide valid results; however, a convergence study should be clearly presented.

The free modal analysis provides all important information. The author clearly identifies the important modes and verifies the mass participation ratio for all axes. Both the random vibration and quasi-static load analyses satisfy the required safety margins and are well documented. The results could also be evaluated for the main structure, particularly the deformation of the rails and its effect on the clearance within the deployer mechanism. In the final chapters, a discussion of the results and possible limitations of the analyses would be beneficial. Additionally, a summary table containing the evaluated values, acceptance criteria, and resulting safety margins would be helpful to the reader.

Some parts of the text appear to be AI-generated or AI-assisted. For example, Section 5.2.4 "Meshing" contains statements such as: "The discretization of the CubeSat finite element model followed a rigorous and structured approach to ensure high-quality element shapes and reliable convergence." Such sentences are very vague and do not provide any information about the actual element sizes used or the targeted mesh quality criteria. Other minor inconsistencies are also present, such as references to "analytical results obtained from this finite element model", whereas an FEM model provides numerical rather than analytical results. Nevertheless, there are no significant errors in the text overall. Topics for thesis defence:

1. Are the boundary conditions for the modal analysis and random vibration analysis true to the real use? How would it change if one of the sides of the structure was preloaded instead of fixed?
2. In the final design, what would be the influence of thermal effects on the structure of the CubeSat?

Points proposed by reviewer: 80