An orthotropic interface damage model for simulating drying processes in soils

Abstract

The study of drying process in soils has received an increased attention in the last few years. This is very complex phenomenon that generally leads to the formation and propagation of desiccation cracks in the soil mass. In recent engineering applications, high aspect ratio elements have proved to be well suited to tackle this type of problem using finite elements. However, the modeling of interfaces between materials with orthotropic properties that generally exist in this type of problem using standard (isotropic) constitutive model is very complex and challenging in terms of the mesh generation, leading to very fine meshes that are intensive CPU demanding. A novel orthotropic interface mechanical model based on damage mechanics and capable of dealing with interfaces between materials in which the strength depends on the direction of analysis is proposed in this paper. The complete mathematical formulation is presented together with the algorithm suggested for its numerical implementation. Some simple yet challenging synthetic benchmarks are analyzed to explore the model capabilities. Laboratory tests using different textures at the contact surface between materials were conducted to evaluate the strengths of the interface in different directions. These experiments were then used to validate the proposed model. Finally, the approach is applied to simulate an actual desiccation test involving an orthotropic contact surface. In all the application cases the performance of the model was very satisfactory.

Simulação do comportamento de ressecamento em solos não saturados utilizando elementos finitos de elevada razão de aspecto

“…O comportamento das descontinuidades sob a forma de fissuras foi reproduzido por meio de elementos de interface com elevada razão de aspecto (high aspect ratio interface elemento -HAR-IE) (Osvaldo L. Manzoli, Cleto, Sánchez, Guimarães, & Maedo, 2019) que foram inseridos entre os elementos da malha original na etapa de pré-processamento (Técnica de Fragmentação da Malha). Tais elementos são representados pelo modelo de dano à tração proposto por Manzoli et al (2017;, cujas equações são resumidas na Tabela 2. O modelo de interface solo-placa foi desenvolvido para admitir, além do dano à tração, degradação ao cisalhamento.…”

Modelling fracture formation and propagation in geo-materials

“…CODE_BRIGHT was developed to deal with continuous porous media and therefore was not able to tackle problems involving the formation and propagation of discontinues. In this work, CODE_BRIGHT was upgraded to simulate evolving fractures by implementing in it the approach suggested by Manzoli et al [13,14,15] that is based on the inclusion of HAR finite elements with tailored mechanical and hydraulic constitutive models to represent the behaviour of discontinuities. The mechanical behaviour of the HAR elements is controlled by a tensile damage model, while the hydraulic response depends on the fracture aperture through the well know cubic law.…”

Modelagem do processo de fissuração em osso cortical através da técnica de fragmentação de malha de elementos finitos.

“…O processo de iniciação e propagação das fissuras pelos elementos com alta razão de aspecto é descrito cobinando dois modelos constitutivos baseados na teoria da mecânica do dano contínuo. Para simular a interface de cisalhamento necessária para descrever o potencial deslizamento tangencial na região representada pela linha de cimento, foi adotado um modelo similar ao proposto por Manzoli et al (2018) definido em função da tensão cisalhante atuante no elemento de interface e a energia de fratura. Em seguida, a abertura de fissuras é representada por um modelo de dano à tração (Manzoli et al, 2016) definido em função da tensão normal atuante no elemento de interface e da energia de fratura da fase do compósito que este elemento está inserido.…”