Essential boundary and interface conditions in the meshless analysis of shells.

• Ano de defesa: 2015
• Autor(a) principal: Costa, Jorge Carvalho
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Cascas (Engenharia); Cisalhamento; Meshless methods; Método de Nitsche; Métodos sem malha; Multi-region problems; Nitsche's method; Problemas multi-regiões; Shear deformable shells; Shells
• Link de acesso: http://www.teses.usp.br/teses/disponiveis/3/3144/tde-24082016-080545/

Meshless methods provide a highly continuous approximation field, convenient for thin structures like shells. Nevertheless, the lack of Kronecker Delta property makes the formulation of essential boundary conditions not straightforward, as the trial and test fields cannot be tailored to boundary values. Similar problem arise when different approximation regions must be joined, in a multi-region problem, such as kinks, folds or joints. This work presents three approaches to impose both kinematic conditions: the well known Lagrange Multiplier method, used since the beginning of the Element Free Galerkin method; a pure penalty approach; and the recently rediscovered alternative of Nitsche\'s Method. We use the EFG discretization technique for thick Reissner-Mindlin shells and adapt the weak form as to separate displacement and rotational degrees of freedom and obtain suitable and separate stabilization parameters. This approach enables the modeling of discontinuous shells and local refinement on multi-region problems.