Experimental measurement of strains using digital volume correlation

Prediction of the effects of material discontinuities and strain concentrations on the failure properties of manufactured parts is difficult when using complicated structural foams and composites. Simplistic modeling approaches do not adequately represent material behavior when the material architectural length scale is of the same order as the geometry of the part. More advanced modeling can be performed; however, the results need to be compared to some measured behavior. This paper uses digital volume correlation (DVC), a three-dimensional full-field non-contacting measurement technique based on high-resolution computed tomography, to quantify strains and visualize microdeformation mechanisms. When applied to an aluminum foam loaded in stage to failure, this technique can quantify the elastic strains, localize the failure region, and visualize the deformed microarchitecture in the failure zones. Comparisons are also made between an experimentally measured strain field in a foam specimen with a large strain concentration and the strain field predicted using an isotropic finite element analysis. The finite element analysis underestimates the magnitude of the strain concentration and the distance over which it has influence.