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Prof. Romana Piat

Prof. Romana Piat

[sci.] Professor at the University of Applied Sciences Darmstadt
Group: Heisenberg
Room: Germany, Darmstadt

h_da Hochschule Darmstadt
fbmn Fachbereich Mathematik und Naturwissenschaften

Schöfferstr. 3
D-64295 Darmstadt






Microstructure modeling and optimization of melt-infiltrated metal-ceramic composites

Research Group of Dr. Romana Piat


Project description


The aim of these studies is to develop a two scale microstructure optimization method for microstructure optimization of the metal-ceramic samples under quasi-static loading. The objective function of the optimization is the macroscopic stiffness. The macroscopic modeling is provided by the finite element method. The microstructure in each integration point of the element corresponds to several domains (areas of the same orientation and geometry of the lamella) and presents the microstructure at the micro level. The effective stiffness of the material on the micro scale will be calculated using a two step homogenization procedure. In the first homogenization step the inelastic material behavior of both micro constituent phases is incrementally calculated. The effective stiffness in the integration point is determined in the second homogenization step. The restrictions on the optimization design variables are to be defined from statistical studies of the microstructure and from the manufacturing process. The solution of the optimal problem is provided for the simple loading case and geometry. Later it will be provided for cup-shaped prosthesis. Experimental data and FE simulations for the real microstructure will be used for determination of the material laws for each micro constituent and for verification of the modeling results.


Typical microstructure of the melt-infiltrated metal-ceramic composites (Photos by Dr. S. Roy IWK1)



Calculated optimal distribution of the lamella orientation and ceramic content in 4 point bending test specimen



a) Schematic representation of the 4-point bending test and of single domain with orientation alpha

b) Optimized microstructure with minimal compliance: Domain and ceramic distribution within the 2D microstructure


More information on the obtained results in

R. Piat, Y. Sinchuk, M. Vasoya, O. Sigmund, Minimal compliance design for metal-ceramic composites based structures, submitted to Acta Materialia.



Nachwuchsgruppe von Dr. Romana Piat


Reviewed Journal Papers and Books (last five years):




Gross T., Nguyen K., Timoshchuk N., Tsukrov I., Reznik B., Piat R., Bohlke T.
Tension-compression anisotropy of in-plane elastic modulus for pyrolytic carbon
accepted in Carbon.


Piat R., Sinchuk Y., Vasoya M., Sigmund O.
Minimal compliance design for metal-ceramic composites based structures
submitted in Acta Materialia.


Drach B., Tsukrov I., Gross T., Dietrich S., Weidenmann K., Piat R., Böhlke T.
Numerical modeling of carbon/carbon composites with nanotextured matrix and 3D pores of irregular shapes
submitted in J. of Solids and Structures.





Sinchuk Y., Piat R., Vasoya M.
Elastic Properties of Metal-Ceramic Composites: Micromechanical Estimation and Microstructure
In Ed: Krenkel W., Lamon J.: High Temperature Ceramic Materials and Composites AVISO Verlagsgesellschaft mbH, Berlin,Germany, 228-233.


Piat R., Dietrich S., Gebert J.-M., Stasiuk G., Weidenmann K., Wanner A., Böhlke T., Drach B., Tsukrov I., Bussiba A.
Micromechanical Modeling of CFCs Using Different Pore Approximations
In Ed: Krenkel W., Lamon J.: High Temperature Ceramic Materials and Composites, AVISO Verlagsgesellschaft mbH, Berlin,Germany, 590-597.


Gebert J.-M., Reznik B., Piat R., Viering B., Weidenmann K., Wanner A., Deutschmann O.
Elastic constants of high-texture pyrolytic carbon measured by ultrasound phase spectroscopy
Carbon, 48(12), 3635-3658.


Böhlke T., Jöchen K., Piat R., Langhoff T.-A., Tsukrov I., Reznik B.
Elastic Properties of Pyrolytic Carbon with Axisymmetric Textures
Technische Mechanik, 30(4), 343-353.


Ziegler T., Neubrand A., Piat R.
Multiscale Homogenization Models for the Elastic Behaviour of Metal/Ceramic Composites with lamellar domains
Composite Science and Technology, 70(4), 664-670.


Böhlke T., Langhoff T.-A., Piat R.
Bounds for the Elastic Properties of Pyrolytic Carbon
PAMM 9, 431-434.


Piat R., Roy S., Wanner A.
Material parameter identification of interpenetrating metal-ceramic composites
Key Engineering Materials, 417-418: 53-56.





Ziegler T., Neubrand A., Roy S., Wanner A., Piat R.
Elastic Constants of Metal/Ceramic Composites with Lamellar Microstructures: Finite Element Modelling and Ultrasonic Experiments
Composites Science and Technology, 69 (5): 620-626.





Bussiba A., Kupiec M., Ifergane S., Piat R., Böhlke T.
Damage evolution and fracture events sequence in various composites by acoustic emission technique
Composite Science and Technology, 68 (5): 1144-1155.


Gebert J.-M., Wanner A., Piat R., Guichard M., Rieck S., Paluszynski B., Böhlke T.
Application of the Micro-Computed Tomography for analyses of the mechanical behavior of brittle porous materials
Mechanics of Advansed Materials and Structures, 15: 467-473.


Bussiba A., Kupiec M., Piat R., Böhlke T.
Fracture characterization of c/c composite under various stress modes by mutual mechanical and acoustical responses
Carbon, 46(4):618-630.


Piat R., Tsukrov I., Böhlke T., Bronzel N., Shrinivasa T., Reznik B., Gerthsen D.
Numerical studies of the influence of textural gradients on the local stress concentrations around fibers in carbon/carbon composites
Communications in Numerical Methods in Engineering, 24(12):2194-2205.


Leguillon D., Piat R.
Fracture of porous materials – Influence of the pore size, Toughness of porous materials
Engineering Fracture Mechanics, 75: 1840-1853.





Piat R., Lapusta Y., Böhlke T., Guellali M., Reznik B., Gerthsen D., Chen T., Oberacker R., Hoffmann M.J.
Microstructure induced thermal stresses in pyrolytic carbon matrices at temperatures up to 29000C
Journal of the European Ceramic Society, 27(16) : 4813-4820.


Piat R., Roser M., Fritzen F., Schnack E.
Numerische Modellierung des Rissfortschritts in porösen CVI-CFC Verbundwerkstoffen
MP Materialprüfung, 49, 170-176.





Piat R.
Numerical modeling of brittle fracture in porous CFC materials
PAMM 6: 191-192.


Piat R., Tsukrov I., Mladenov. N., Verijenko V., Guellali M., Schnack E., Hoffmann M. J.
Material modeling of the CVI-infiltrated C-felt. I. Basic formulae, theory and numerical experiments
Composites Science and Technology 66(15):2997-3003.


Piat R., Tsukrov I., Mladenov. N., Guellali M., Ermel R., Beck T., Schnack E., Hoffmann M. J.
Material modeling of the CVI-infiltrated C-felt. II. Statistical study of the microstructure, numerical analysis and experimental validation
Composite Science and Technology 66(15): 2769-2775.



Junior Research Group of Dr. Romana Piat


 Dr. Romana Piat

Dr. Romana Piat



 Dipl.-Math. Galyna Stasiuk

Dipl.-Math. Galyna Stasiuk

Scientific Employee

 Dr. Yuriy Sinchuk

Dr. Yuriy Sinchuk

Post Doc