Experimental characterization of the local strain field in a heterogeneous elastoplastic material

A new technique, which allows to characterize the local strain field over a domain representative of the microstructure of a heterogeneous material, is described. It is based on scanning electron microscopy, microelectrolithography, image analysis and in situ tensile tests. The in-plane components of the local strain field are characterized by their averages per phase and their distribution functions. The results are accurate for global strains between 5 and 15%. It is also possible to get contour plots of these components of the local strain field over the considered domain. The obtained strain maps give a powerful qualitative information on the strain localization modes during the deformation. This technique has basically been developed for two-phase elastoplastic materials, namely iron/silver and iron/copper blends, submitted to uniaxial tensile tests; it could also be used for polycrystals or other composite materials and for other mechanical tests.

[1]  Daniel Post,et al.  Moiré interferometry: Advances and applications , 1991 .

[2]  M. Kujawinska,et al.  Automated fringe pattern analysis for moiré interferometry , 1993 .

[3]  P. Ifju,et al.  Geometric moiré methods with enhanced sensitivity by optical/digital fringe multiplication , 1993 .

[4]  M. Coster,et al.  Précis d'analyse d'images , 1989 .

[5]  C. E. Taylor,et al.  An application of pattern mapping to plane motion , 1990 .

[6]  Bongtae Han,et al.  Immersion interferometer for microscopic moiré interferometry , 1992 .

[7]  David T. Read,et al.  Scanning moiré at high magnification using optical methods , 1993 .

[8]  M. Sutton,et al.  Effects of subpixel image restoration on digital correlation error estimates , 1988 .

[9]  J. S. Sirkis,et al.  Displacement pattern matching and boundary-element methods for elastic-plastic stress analysis , 1990 .

[11]  Akira Kawasaki,et al.  Fine-grid method for large-strain analysis near a notch Tip , 1983 .

[12]  Rodney Hill,et al.  Continuum micro-mechanics of elastoplastic polycrystals , 1965 .

[13]  J. S. Sirkis,et al.  Displacement and strain measurement with automated grid methods , 1991 .

[14]  R. Christensen,et al.  Solutions for effective shear properties in three phase sphere and cylinder models , 1979 .

[15]  P. Hazzledine,et al.  A fiducial grid for high-resolution metallography , 1976 .

[16]  K. Hatanaka,et al.  A measurement of three-dimensional strains around a creep-crack tip , 1992 .

[17]  A. Zaoui,et al.  Modelling the effective behavior of nonlinear matrix-inclusion composites , 1990 .

[18]  M. A. Sutton,et al.  Accurate measurement of three-dimensional deformations in deformable and rigid bodies using computer vision , 1993 .

[19]  W. F. Ranson,et al.  Applications of digital-image-correlation techniques to experimental mechanics , 1985 .

[20]  James S. Sirkis,et al.  System response to automated grid methods , 1990 .

[21]  Hugh Alan Bruck,et al.  Full-field representation of discretely sampled surface deformation for displacement and strain analysis , 1991 .

[22]  W. F. Ranson,et al.  Determination of displacements using an improved digital correlation method , 1983, Image Vis. Comput..