Finite element modeling of abradable materials – Identification of plastic parameters and issues on minimum hardness against coating's thickness

Abstract

-Abradable materials are used to decrease the gas consumption of aircraft engines by minimizing the gap between the blade tips and the stator. The key idea consists in using the blades themselves to machine the gap on the abradable coating. The best compromise between soft and hard coating properties has to be reached to avoid blades wear and prevent coating erosion by gas flux and particles. The plastic parameters of abradable coating were identified by using an optimization process directly connected to FEA. The first order optimization method (conjugate gradient strategy + golden section algorithm) was applied to achieve the optimal solution. A good agreement was found between experimental and numerical results. The plastic parameters were used to study the hardness variability of abradable materials with the coating thickness. Surprisingly, a minimum hardness value was found while it was expected that hardness should be always decreasing with thickness. It has been demonstrated that this minimum is produced by the boundary conditions influence on hardness measurement. This research work was completed within the Seal-Coat project funded by the European Commission under the FP5 Growth Program.

Numerical-Experimental Comparison in the Simulation of Rotor/Stator Interaction Through Blade-Tip/Abradable Coating Contact

“…If the experimental static characterization of this material [16,17] is known, the dynamic characterization is still being investigated [18]. For instance, the finite element method combined with an optimization procedure is employed in [19] for the simulation of the HR15Y hardness test on abradable material. It was shown that a bilinear plastic law could accurately represent the mechanical behavior of abradable material.…”

Numerical Investigation of Abradable Coating Wear Through Plastic Constitutive Law: Application to Aircraft Engines

“…In order to better estimate the wear parameter, comparisons with experimental results such as the ones presented in [14,15] have to be scheduled in a near future. Other approaches in the form of frequency-domain formulated nonlinear normal modes may be relevant for faster parameter studies [8].…”

Modélisation plastique bi-linéaire de l’usure de matériaux abradables : application aux turbo-machines

“…L'identification expérimentale de ces matériaux est sujet de nombreuses études [5] mais leur modélisation dans des configurations réalistes semble limitée.…”