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Influence of specimen preparation, microstructure anisotropy, and residual stresses on stress–strain curves of rolled Al2024 T351 as derived from spherical indentation tests

Published online by Cambridge University Press:  31 January 2011

J. Heerens ,
F. Mubarok  and
N. Huber
J. Heerens*
Affiliation:
GKSS Research Centre Geesthacht, Institute of Materials Research, Materials Mechanics, 21502 Geesthacht, Germany
F. Mubarok
Affiliation:
GKSS Research Centre Geesthacht, Institute of Materials Research, Materials Mechanics, 21502 Geesthacht, Germany
N. Huber
Affiliation:
GKSS Research Centre Geesthacht, Institute of Materials Research, Materials Mechanics, 21502 Geesthacht, Germany
*
a) ddress all correspondence to this author. e-mail: [email protected]
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Abstract

In the present work, a previously developed neural network approach for analyzing spherical indentation experiments is applied to prestressed specimens to determine the effect of residual stresses on the identified stress–strain curves. Within this scope, a comparison to other measurement errors has been made, which are caused by surface preparation and anisotropy of the material. To validate the experimental and analysis approach, the effect of compressive and tensile prestresses was also simulated using a three-dimensional finite element model. The material investigated is a rolled 2024 T351, which is widely used for manufacturing airplanes. It is shown that the existing neural network approach is able to determine the stress–strain behavior in agreement with that obtained from tensile tests. The method is robust against most error sources, such as surface roughness, coarse grain structure, and anisotropy, if a sufficient number of experiments are available. The most important influencing factor can be the residual stress causing errors up to 20% in the identified stress–strain curves.

Keywords

AlHardnessStress/strain relationship
Type
Articles
Information
Journal of Materials Research , Volume 24 , Issue 3 , March 2009 , pp. 907 - 917
Copyright
Copyright © Materials Research Society 2009

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References

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