Experimental and numerical characterisation of in-plane deformation in two-phase materials☆
Introduction
Stress and strain distribution in two-phase materials under loading is inhomogeneous. The magnitude of the inhomogeneity as well as local strain patterns depend on the microstructure (i.e. the elastic–plastic behaviour, volume fraction and phase arrangement of the components). The knowledge of the microstructure/deformation-relationship enables “tailoring” of materials with desired profiles of properties. The critical concentration of strain, stress or hydrostatic stress can lead to damage initiation and failure of the component. By an optimised microstructure design such stress and strain concentrators can be avoided or reduced.
Section snippets
Material and microstructure
The subject of the following experimental and numerical investigations is a model material Ag/Ni(57%)-particulate composite with a coarse microstructure with an average Ni-phase size of and an Ag-phase size of (Table 1). This material was produced by a powder metallurgical route using hot isostatic pressing (HIP 900°/200 MPa/1 h) [1]. Ag and Ni as mutually insoluble elements exist in a composite as “pure” phases without any transient zone. This is the reason that this material's
Compression test and an object grating technique
The Ag/Ni-material has been tested under uniaxial compression in the chamber of a scanning electron microscope using a specific in situ compression device that is able to generate loads of up to 10 000 N. A cylindrical sample (6 mm diameter and 8 mm length) with a Rastegaev-type geometry [3] and grease at both sides of the sample in order to reduce friction was used. Two symmetric flat planes were manufactured along the sample in order to facilitate the observation with the SEM. One of these was
Discussion
Experimental and numerical investigations on the same cut-out of the Ag/Ni-particulate composite have been performed in order to correlate in-plane strain components and out-of-plane displacements. The comparison of the results influenced the development and improvement of all these methods.
For the numerical simulation it can be concluded that 2D-calculations provide results with a good qualitative agreement but they are not able to reproduce the experimental details quantitatively. For this
Conclusions
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Corrections of the equivalent strain performed using out-of-plane displacements in an Ag/Ni-composite as measured by AFM at a macroscopic deformation of 8.6% are negligibly small.
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The comparison between experimental and calculated distributions of equivalent strains shows a good qualitative agreement – quantitative agreement is expected for the case of well-defined experimental boundary conditions as well as 3D-calculations instead of a 2D-simulation. In the case of coarse grain size comparable
Acknowledgements
This work was performed in the frame of the PROCOPE-Project “Experimental and numerical investigations of the deformation in Ag/Ni-particulate composites: correlation between in-plane-, out-of-plane-deformation and microstructure” and Research Group “Investigation of the deformation behaviour of heterogeneous materials by direct combination of experiment and computation”, subproject DFG Schm 746/16-1, 2. The authors gratefully acknowledge the financial support by the APAPE, DAAD and Deutsche
References (10)
- et al.
Experimental characterization of the local strain field in a heterogeneous elastoplastic material
Acta Metall.
(1994) - E. Soppa, Arbeitsbericht zum Teilprojekt 2 (Prof. S. Schmauder) “Einfluß der Mikrostruktur auf das...
- et al.
Sonderbände der prakt
Metallographie
(1993) - E. Soppa, Experimentelle Untersuchung des Verformungsverhaltens zweiphasiger Werkstoffe, VDI Verlag, Reihe 5, Nr. 408,...
- P. Doumalin, M. Bornert, D. Caldemaison, Microextensometry by image correlation applied to micromechanical studies...
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