Formulação em dano concentrado para meios contínuos bidimensionais com localização de deformações em modo I

• Autor(a) principal: Santos, Danilo Menezes
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFS
• Texto Completo: https://ri.ufs.br/jspui/handle/riufs/17891
• topic: Mecânica do dano expandida; Localização de deformações; Elementos finitos; Modo I; Chapas; Não linearidade física; Efeito de escala; Extended lumped damage mechanics; Strain localization; Finite elements; Mode I; Thin plates; Physical nonlinearity; Size-effect; ENGENHARIAS::ENGENHARIA CIVIL

The structural integrity is directly influenced by the characteristics of materials using in structures. Materials with nonlinear behavior such as concrete, steel and geomaterials in their softening phase there is a tendency for the appearance of small regions with a high concentration of total deformations, plastic and damage. This phenomenon, sometimes, is not predicted during the dimensioning stage and its occurrence characterizes a special type of collapse known as a failure due to strain localization. In numerical simulations, the phenomenon of strain localization is related to loss of ellipticity in the differential equation that governs the local static or dynamic equilibrium. The loss of ellipticity causes in finite element analysis, with constitutive models based on the Continuum Damage Mechanics, the appearance of infinite solutions, which leads to ill-posed problems. This situation can be overcome by adopting regularization criteria, based mainly on non-local models and/or gradients. Recently, the approach known as Extended Lumped Damage Mechanics (XLDM), has been obtaining quite satisfactory results for the description of the phenomenon of localization in plate and 2D continuum elements. As in the Lumped Damage Mechanics (LDM), the XLDM seeks to circumvent the loss of ellipticity of solutions by introducing new kinematic variables to the equilibrium problem. This work is a continuation of the existing studies related to XLDM. A quadrilateral isoparametric finite element is proposed here, consisting of 6 location bands, four located on their faces and two internal, for analysis of plates submitted to mode I stress. The proposed element was applied to a set of examples obtaining uniqueness of solution as the mesh refinement occurred, in addition to obtaining rupture zones consistent with the expected. Furthermore, the XLDM was able to capture the scale effect, a phenomenon observed experimentally.