Biaxial flexural strength in Y-TZP and finite element simulation (FEM)

Reference Presenter Authors
(Institution)
Abstract
09-053 Leonardo Queiroz Bueno Campos SANTOS, C.(UERJ); da Silva, P.C.(Universidade Federal Fluminense); Simba, B.G.(UNESP-FEG); Alves, M.F.(Universidade do Estado do Rio de Janeiro); Moreira, L.P.(Universidade Federal Fluminense); Campos, L.Q.(Universidade estadual do Rio de Janeiro); In this work, the bending strength of yttria-stabilized tetragonal zirconia polycrystal, Y-TZP, was evaluated using biaxial bending test and, comparatively, from mathematical modelling using finite element method (FEM). Y-TZP samples were compacted at 100MPa and sintered at 1530°C-2h. Specimens, n=30, (14mm diameter x 1.2mm thickness) were characterized by X-ray diffraction, scanning electron microscopy, relative density, Young modulus and Poisson ratio. Biaxial bending tests were performed (ISO6872), using an apparatus composed of a piston and a base with three tempered-steel spheres. From the results, numerical simulations of the biaxial bending tests were performed using ABAQU/Standard v-6.9 software. The complete model used 70,216 elements considering the components of the test. The results point to complete densification with relative density higher than 99.5%, ZrO2-tetragonal as crystalline phase and average grain size of 0.6±0.2?m. The mechanical characterization indicated Young modulus of 203±5GPa, Poisson ratio of 0.27, flexural strength of 1210±120MPa and Weibull modulus m=8. The results of the MEF simulation indicate a biaxial flexural strength close to 400MPa. The difference of values found (1210MPa-400MPa) is discussed because this ceramic presents a peculiar toughness mechanism based on tetragonal-monoclinic phase transformation, which is not recognized by the software, and therefore does not appear in the traditional numerical analysis. Thus a mathematical factor is inserted in the basic equations from the software aiming the correction and adjustment of the program to the peculiarities of this ceramic material.
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