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LIMIT ANALYSIS ON SCRATCH TEST PROBLEM

Figueiredo, F. C.; Borges, L. M. S. A.;

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Scratch test is one of the oldest method to determine mechanical properties in materials. The technique has gained interest due to the properties implied during test, such as adherence, hardness, cohesion and elasticity. On this test a rigid indenter is dragged on the material test surface at a constant depth and controlled forces. This problem is modeled by finite elements method and limit analysis theory, which is is a direct method and there is no need to calculate stresses during each load step in order to compute critical states and collapse mechanisms. From virtual power principle, the internal power is related to the external power, which is amplified by load factor so that the body achieves a plastic collapse. The solution of a limit analysis problem is to find this load factor, the plastically admissible stresses fields that are in equilibrium with the given forces system, the kinematically admissible velocity fields, the strain rate field , which is related to the velocity field by means of a deformation operator, and the plastic multiplier. The solution of a limit analysis problem closely depends on the yield function that describes the behavior of a material, such as von Mises for metals and Drucker-Prager for rocks. However, traditional criteria for rocks and soils such as Mohr- Coulomb and Drucker-Prager do not consider material porosity. Therefore, an yield criterion that includes porosity effect is applied in this work. This function is applied to the discretized limit analysis model. A semi-analytical solution based on limit analysis lower bound method is developed and the proposed yield function is also applied. Then, the results between both methods are compared.

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Palavras-chave: Limit Analysis, Finite Elements, Porous Materials, Lower-Bound Solution,

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DOI: 10.5151/meceng-wccm2012-18593

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Como citar:

Figueiredo, F. C.; Borges, L. M. S. A.; "LIMIT ANALYSIS ON SCRATCH TEST PROBLEM", p. 1929-1944 . In: In Proceedings of the 10th World Congress on Computational Mechanics [= Blucher Mechanical Engineering Proceedings, v. 1, n. 1]. São Paulo: Blucher, 2014.
ISSN 2358-0828, DOI 10.5151/meceng-wccm2012-18593

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