Strain Measurement in an Aluminium Foam by Means of Digital Image Correlation - Visual Computing: Scientific Visualization and Imaging Systems - page 130

Chapter 7
Strain Measurement in an Aluminium
Foam by Means of Digital Image
Correlation
Luca Goglio, Marco Peroni and Jakson Manfredini Vassoler
Abstract Metallic foams represent a particular class of materials, characterized
by their cellular internal structure, which are receiving a growing interest for
lightweight construction and impact absorbers. The inhomogeneity makes it dif-
ficult to measure the strain with conventional techniques (e.g. strain gauges); on
the contrary, an optical non-contact technique is particularly suitable, taking
advantage of the naturally speckled surface. This chapter presents the application
of the Digital Image Correlation (DIC) to the study of the response of an alu-
minium foam subjected to compression. A key aspect of the mechanical charac-
terization of the foam is to evaluate the influence of the density on the sensitivity to
the loading rate. The measuring technique encompasses two steps: first the dis-
placements of a set of marker points are tracked using image analysis; then the
strains are evaluated by means of a strain-displacement relationship, in which the
markers play the role of the nodes in finite element modelling. The results allow
for evaluating the evolution of the strains in the material during the compression
test.
Keywords Digital image correlation Metallic foams Compression testing
Strain measurement