Miniature Marciniak setup for in-situ SEM observation ofdamage micro-mechanismsCitation for published version (APA):Hoefnagels, J. P. M., Tasan, C. C., Dekkers, E. C. A., & Geers, M. G. D. (2010). Miniature Marciniak setup forin-situ SEM observation of damage micro-mechanisms. In F. Bremand (Ed.), ICEM 14 – 14th InternationalConference on Experimental Mechanics (pp. 16009-). (EPJ Web of Conferences; Vol. 6). France: EDPSciences. DOI: 10.1051/epjconf/20100616009

DOI:10.1051/epjconf/20100616009

Document status and date:Published: 01/01/2010

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Miniature Marciniak Setup for in-situ SEM Observation of Damage Micro-mechanisms

J.P.M. Hoefnagels1,a, C.C. Tasan1,2, E.C.A. Dekkers3, M.G.D. Geers1

1 Eindhoven Univ. of Tech., Dept. of Mech. Engg., P.O.Box 513, 5600MB, Eindhoven, Netherlands. 2 Materials Innovation Institute (M2i), P.O.Box 5008, 2600GA, Delft, Netherlands. 3 Eindhoven Univ. of Tech., Joint Technical Department, P.O.Box 513, 5600MB, Eindhoven, Netherlands.

1 Scientific relevance

The industrial and scientific interest for ductile damage and fracture has significantly increased in

the last decades due to the popularity of new advanced materials, such as high strength steels and

nanostructured metals [1]. To allow for detailed investigation of micro-events such as the damage

micro-mechanisms, the deformation needs to be studied in real time with in-situ scanning electron

microscopy, allowing for digital image correlation (DIC) of the high resolution images for local

strain mapping [2], see e.g. Figure 1. These studies, however, were limited to deformation under uni-

axial tension due to the constraints of in-situ SEM testing.

At the same time, parallel research efforts have focused on elucidating the effect of the followed

strain path on the ductile deformation micro-mechanisms, and its consequence for the resulting

macroscopic forming and fracture limits in sheet metal [3]. Unfortunately, in these studies the

damage micro-mechanisms were studied from post-mortem fracture analysis [4], due to the absence

of a miniaturized testing setup capable of deforming sheet metal up to failure in alternative strain

paths (e.g. plane strain or biaxial tension).

Fig. 1. SEM image and effective strain overlay at 4 different deformation stages for dual phase steel [7].

a e-mail: j.p.m.hoefnagels@tue.nl

© Owned by the authors, published by EDP Sciences, 2010DOI:10.1051/epjconf/20100616009EPJ Web of Conferences 6, 16009 (2010) 6

This is an Open Access article distributed under the terms of the Creative Commons Attribution-Noncommercial License 3.0, which permits unrestricted use, distribution, and reproduction in any noncommercial medium, provided the original work is properly cited.

Article disponible sur le site http://www.epj-conferences.org ou http://dx.doi.org/10.1051/epjconf/20100616009

14th International Conference on Experimental Mechanics

2 Research goal and results

In this work, we set out to develop a test setup that allows for deformation of sheet metal at various

strain paths up to the point of fracture under in-situ SEM observation. Figure 2(a) shows an

experimental-numerical analysis of candidate testing setups (bulge test, Nakazima test, cruciform

test, and Marciniak test), which identified the Marciniak test setup as the most suited for

miniaturization [5]. Still, significant design challenges were identified, including (i) high load levels

(>100 kN) to be reached within the (small) SEM-chamber, (ii) forcing fracture to occur inside the

“contactless“ gauge section, and (iii) assuring the safety of the electron microscope.

(a) (b)

Fig. 2. (a) experimental/numerical evaluation of candidate multi-axial test setup for miniaturization, and (b) the

final design of the miniaturized Marciniak Setup with the SEM vacuum chamber depicted in blue.

These challenges were successfully addressed and an in-situ miniaturized 150kN Marciniak setup

(Figure 2(b)) was designed and built, which allows for world-first experimentation of multi-axial

testing of sheet metal up to fracture under in-situ SEM observation. A case study is presented, in

which strain-dependent damage initiation from microstructural bands in steels is investigated from

SEM-DIC strain maps.

1. S. Sadagopan. et al., AISI/DOE Technology Roadmap Program, 2003; K.S. Kumar. et al., Acta Mater., 51

(2003) 5743.

2. J. Kang, et al., Scripta Mater., 56 (2007) 999; C.C. Tasan, J.P.M. Hoefnagels, M.G.D. Geers, submitted for

publication.

3. T. Kuwabara. et al., Int. J. Plasticity, 23 (2007) 385.

4. C.C. Tasan, J.P.M. Hoefnagels, M.G.D. Geers, Scripta Mater., 61 (2009) 20; C.C. Tasan, J.P.M.

Hoefnagels, C.H.L.J. Ten Horn, M.G.D. Geers, Mech. Mater., 41 (2009) 1264.

5. C.C. Tasan, J.P.M. Hoefnagels, M.G.D. Geers, Proceeding of the SEM XI conference (2008); G. Quaak,

M.Sc. Thesis, Eindhoven University of Technology (2008).

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