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Competition between global and local instabilities in the failure of aeronautical structures

Abstract : Aeronautical engineers are constantly challenged to provide lighter structures in order to reduce fuel consumption, and thus the environmental impact and flight costs. At the same time, the design of aeronautical structures is subjected to strict regulation aimed at ensuring the integrity of the aircraft and the safety of the passengers. To tackle this challenge, the limits of structural and material mechanics are consistently explored which in turn leads to the development of new, mathematical, numerical, experimental and manufacturing tools.There are numerous metallic parts in the most critical aeronautical structures, like landing gears, engine shafts, or mechanical lugs. These parts are subjected to extreme loading conditions due to the thermal environment or to the intense mechanical ultimate or cyclic loading. The failure of these elastoplastic structures is generally caused by the initiation and propagation of cracks or by the emergence of local instabilities, such as plastic strain localization, or global instabilities, such as buckling.In the present work, we focus on the detection of local and global elastoplastic instabilities in a finite deformation framework. While they are generally studied separately, it was chosen to study both phenomena together in order to analyze and better understand the competition between localization and buckling in elastoplastic structures. For this purpose, multiple analytical developments are presented founded on Hill's global stability criterion (1958) and Rice's strain localization criterion (1976). The new "weakened stability analysis" has been introduced in order to analyze the sensitivity to the type of prescribed boundary conditions. All these criteria have been implemented in the finite element software Zset, which allowed us to analyze the emergence of elastoplastic instabilities in various experimental samples, tubes loaded in torsion, and a lug loaded in tension.
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Submitted on : Friday, November 29, 2019 - 3:13:22 PM
Last modification on : Friday, March 25, 2022 - 3:22:20 AM


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  • HAL Id : tel-02386956, version 1


Moubine Al Kotob. Competition between global and local instabilities in the failure of aeronautical structures. Materials. Université Paris sciences et lettres, 2019. English. ⟨NNT : 2019PSLEM002⟩. ⟨tel-02386956⟩



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