Análise do efeito de escala em materiais quase frágeis

Abstract

The structural size effect studies the variation in the behaviour of structures when they change size. This effect appears in various types of materials, geometries and boundary conditions. No doubt, this phenomenon cannot be ignored when the nonlinear behaviour study of solids is carried out until fracture. In this work, the experimental study of simple tension tests and acoustic emission tests in samples of expanded polystyrene with different sizes is first analyzed. Results in terms of stress, strain, acoustic events and final configurations are obtained. These results are compared with the simulated ones obtained using a version of the truss-like discrete element method. This method consists of a representation of the continuum through a regular lattice arrangement of uniaxial elements where the masses are concentrated on the nodes and the element stiffness represents the behaviour of the portion of continuum modeled. Final configurations, as well as the stress-strain curves, are obtained in numerical form (this information can directly be compared with the obtained experimental values). It is also possible to present results in terms of energy balance during the fracture process, as well as simulate measurements of acoustic emission signals (accelerations issued in different places of the model) during the simulation. The obtained parameters allow calculating specific indicators which allow monitoring the fracture process. The experimental and numerical results are compared and discussed focusing attention to the size effect that the obtained information presents.