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Finite element analysis of indentation experiments using visco-plastic material models

: Olaf, J.M.; Sester, M.; Hönig, A.; L'Huillier, P.


Computational materials science 3 (1994), Nr.2, S.218-222
ISSN: 0927-0256
Workshop on Computational Modelling of the Mechanical Behaviour of Materials <3, 1993, Stuttgart>
Fraunhofer IWM ()
chaboche; creep; cyclic loading; Dehnratenabhängigkeit; Eindrucktechnik; finite element analysis; Finite-Elemente-Methode (FEM); indentation technique; Kriechen; large deformations; needleman; rate dependence; viscoplastic material behaviour; viskoplastisches Materialverhalten; zyklische Belastung

The indentation experiment is commonly used for the characterization of surfaces, thin films, and small sized elements. However, due to the complex parameter dependencies the experimental results are significantly affected by the influence of these parameters and cannot easily be interpreted. Therefore finite element calculations on the indentation process are carried out in order to analyze the deformation and stress distribution under the indenter as reported in [1] and [2]. In this contribution it is shown, that even materials with very complex (timedependent) properties can be investigated if corresponding viscoplastic material models are used. After a short introduction of the viscoplastic material models of Needleman and Chaboche & Lemaitre the limiting cases of these models are discussed. The models are applied to the analysis of Vickers' indentations in steel (22 NiMoCr 3 7) with a pronounced timedependent deformation behaviour even at room temperature. The numerical results us ing the two viscoplastic models are compared with each other and with experimental results.