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Probing the Buckling of Thin Shell Space Structures

Friday, May 14, 2021
3:00pm to 4:00pm
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Fabien Royer
Fabien Royer, PhD Candidate, Aeronautics, GALCIT,

From eggshells to sea urchins, shell structures can be found almost everywhere in nature. Their high load bearing capabilities and very low mass have been instrumental in the development of airplanes and rockets throughout the 20th century. In the past decade, the field of satellite structures witnessed a growing use of thin shells, as they enable large deployable structures to be built. They allow for the extremely efficient packaging of large systems which would be impossible to launch otherwise. However, as spacecraft become larger, and the shells become thinner, the range of operations of such structures is limited by buckling. Thin shell buckling is extremely hard to predict because of its large imperfection sensitivity. Even a geometric defect with an amplitude in the order of the shell thickness can cause a dramatic reduction in buckling load. To cope with this unpredictable behavior, buckling criteria have been developed for cylindrical and spherical shells, an provides a lower bound on the statistical load reduction observed in a large number of experiments on near perfect, and imperfect shells. Even if this method proved to yield safe designs, it is now seen as very conservative since it takes into account the most severe type of imperfections. However, it has been shown recently, for the cylindrical shell, that the onset of buckling corresponds to the formation of a single dimple in the structure, and a new methodology has been developed to characterize its formation by locally displacing the shell using a probe. The overarching goal of the research presented in this talk is to apply and extend the probing methodology to complex thin shell space structures, through simulations and experiments. Probing unveils the physics of the structure close to buckling and can be used to determine tighter and more deterministic buckling criteria. It provides the opportunity to develop more efficient structures, used closer to their buckling load than ever before, and even beyond. It would result in dramatically lighter structures and has the potential to enable new applications, such as extremely large space solar power spacecraft, currently developed at Caltech.

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For more information, please contact Benjamin Riviere by email at [email protected].