Title: Fracture simulation of brittle materials in tension and compression using cohesive elements

Abstract

Finite element models using cohesive elements have been used for decades to simulate the fracture in brittle materials. These models provided excellent results in cases where samples are mainly under tensile loadings and, to some degree, under shear states. However, they cannot adequately simulate cases under predominant shear stress, which is the case, for example, cases under unconfined compression loadings. Most constitutive models for cohesive elements are based on frictional envelopes and the plasticity theory. This work aims to extend the current approach used in the constitutive modeling for cohesive elements to predict brittle fracture under prevailing shear stress conditions. For this purpose, a plasticity-based model is proposed. In this model, the initial state of the yield function is given by a strength envelope that is tangent to the compressive and tensile Morh’s circles. Also, the model considers the strength reduction due to cracking by modifying the curvature of the yield function. These features allow the accurate simulation of shear fracture under different normal stress levels. The model was successfully applied to cases usually challenging to simulate using cohesive elements, such as fracture under compression loads and indirect tensile tests. The work also presents the application to RC structures showing good agreement with experimental results.

Biography

Raul Dario Durand Farfan is a PhD in Civil Engineering and a full-time professor at the Civil and Environmental Department at the University of Brasilia, Brazil. His research is mainly concentrated on the following areas: (1) computational models for fracture in brittle materials; (2) computational models for reinforced media such as reinforced concrete (RC) and soil mass; and (3) the development of general finite element formulations to solve differential equations. He published several papers on finite elements on topics such as mesh smoothing, constitutive models for concrete, numerical simulation of reinforced concrete structures, and simulation of coupled problems. Currently is working on constitutive models to simulate masonry using the micromodeling approach. He is also working with thermomechanical and hydromechanical simulations using finite elements.