F. Peyraut, University of Technology of Belfort-Montbeliard, Belfort Cedex, France; J. J. Seichepine, H. I. Faraoun, Belfort-Montbéliard University of Technology, Belfort Cedex, France; C. Coddet, University of Technology Belfort-Montbeliard, Belfort Cedex, France; M. Hertter, MTU Aero Engines GmbH, München, Germany
The aim of our work is twofold. The first objective is to compute abradable material parameters by an optimization process directly connected to a FE analysis. The second objective of this work is to perform an extensive study of the influence of coating thickness on hardness by using a finite element model of the HR15Y hardness test. To identify plastic parameters by indentation test, material properties are fitted in such a way that measured and computed hardness are matched. By using the FE code ANSYS and assuming a bilinear plastic law for the coating, the difference between measured and computed hardness has been minimized. Among various methods offered by ANSYS, the first order optimization method is selected to achieve the optimal solution and excellent agreement between computed and measured hardness has been found. To match up experimental and computational results, two coating thicknesses (1.2 and 2.3 mm) are considered together. We have next performed an extensive study of hardness against thickness by using an axisymmetrical FE model of the HR15Y indentation test. According to the ‘ten times indentation depth’ rule-of-thumb, the indentation depth should not exceed a tenth of the coating thickness but this rule is not a universal law as it is outlined. Our results are in agreement with this conclusion. Particularly, by varying the thickness e as a parameter in the FE model, it is shown that the ratio of thickness to the depth of indentation should exceed 63 to obtain a single hardness value independent on coating thickness. It was also found that the remaining plastic zones must be located far away from the coating boundary (about 60% of the total thickness) to prevent boundary condition influence.
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