During the last two decades, the use of hydrogen (H₂) as fuel for aircraft applications has been drawing attention; more specifically, its storage in liquid state (LH₂), which is performed in extreme cryogenic temperatures (−253 °C), is a matter of research. The motivation for this effort is enhanced by the predicted growth of the aviation sector; however, it is estimated that this growth could be sustainable only if the strategies and objectives set by global organizations for the elimination of greenhouse gas emissions during the next decades, such as the European Green Deal, are taken into consideration and, consequently, technologies such as hydrogen fuel are promoted. Regarding LH₂ in aircraft, substantial effort is required to design, analyze and manufacture suitable tanks for efficient storage. Important tools in this process are computational methods provided by advanced engineering software (CAD/CAE). In the present work, a computational study with the finite element method is performed in order to parametrically analyze proper tanks, examining the effect of the LH₂ level stored as well as the tank geometric configuration. In the process, the need for powerful numerical models is demonstrated, owing to the highly non-linear dependence on temperature of the involved materials. The present numerical models’ efficiency could be further enhanced by integrating them as part of a total aircraft configuration design loop.

When catastrophic failure phenomena in aircraft structures, such as debonding, are numerically analyzed during their design process in the frame of “Damage Tolerance” philosophy, extreme requirements in terms of time and computational resources arise. Here, a decrease in these requirements is achieved by developing a numerical model that efficiently treats the debonding phenomena that occur due to the buckling behavior of composite stiffened panels under compressive loads. The Finite Element (FE) models developed in the ANSYS© software (Canonsburg, PA, USA) are calibrated and validated by using published experimental and numerical results of single-stringer compression specimens (SSCS). Different model features, such as the type of the element used (solid and solid shell) and Cohesive Zone Modeling (CZM) parameters are examined for their impact on the efficiency of the model regarding the accuracy versus computational cost. It is proved that a significant reduction in computational time is achieved, and the accuracy is not compromised when the proposed FE model is adopted. The outcome of the present work leads to guidelines for the development of FE models of stiffened panels, accurately predicting the buckling and post-buckling behavior leading to debonding phenomena, with minimized computational and time cost. The methodology is proved to be a tool for the generation of a universal parametric numerical model for the analysis of debonding phenomena of any stiffened panel configuration by modifying the corresponding geometric, material and damage properties.

The use of liquid hydrogen (LH₂) as a zero-emission energy carrier is increasingly relevant for next-generation transport systems, requiring reliable cryogenic storage solutions operating at approximately −253 °C. This study presents a computational analysis of LH₂ storage tanks, focusing on the coupled thermal–structural behavior of insulated cryogenic vessels under varying design parameters. The present work expands upon our previous effort by employing the Finite Element Method (FEM) to perform a parametric investigation of these tanks. This is accomplished by examining the effect of the insulating material and the change in the storage volume of LH₂, as well as the change in the selected hydrogen boil-off rate (BOR). Results show that increasing the BOR from 0.1%/h to 1.0%/h reduces the required insulation thickness and mass by approximately 90% across all configurations, significantly altering system-level mass distribution. Substituting polyurethane foam (PUR-64) with lower-density equivalent (PUR-32) yields heat-flow reductions of up to 19.5% in two configurations, while producing an unexpected increase of approximately 10% in one case due to nonlinear thermal-gradient effects. Furthermore, increasing the hydrogen storage volume from 50 m³ to 150 m³ enhances gravimetric efficiency by 58%, 75%, and up to 104% depending on tank geometry. The results demonstrate the demand for robust numerical models, due to the nonlinear dependence of the materials involved with temperature.