Estudo da fratura e da propagação de ondas em um meio sólido utilizando o método dos elementos discretos composto por barras no ambiente Abaqus

Abstract

Evaluation of structures in failure situation with numerical methods is always a good option in terms of cost. Said that, present work has the main aim to apply two different numerical models together to realize a study of the acoustical emission provided by a waveguide that fails according to the modes of fracture mechanics applying as the main enviorment the commercial software Abaqus. The Lattice Discrete Element Method (LDEM) is implemented in Abaqus enviorment to represent the portion of the body that ruptures can occur and the Finite Element Method is used to represent the continuous portion. The study is performed simulating the acoustical emission of a waveguide where a induced rupture occurs in a weakened region. The set of the boundary is made ensuring the rupture to occur at the three fundamental modes of fracture mechanics. The results are evalued by multichannel analysis of surface-waves (MASW) methodology and the dispersive profile is plotted by double fast-fourier transform (2DFFT). For each fracture mechanics mode the results found by means of double fourier transform of signals are compared to the dispersion curves of the geometry that were early performed for the main modes of propagation. The fracture mechanics mode I signals excited purely the longitudinal modes, the mode II signals did not show any kind of propagation modes likely the signals that are found at white noises. For mode III analysis three fundamental distinct modes were excited, being bending, torsion and tension/compression modes. From work, it is concluded that the acoustical emissions in fracture mechanics modes exhibit dispersive patterns that can be determined and used to monitoring and assessment the sctructural integrity increasing the safety margin to failure.