Figure 7: Evolution of the cross section of a monofilament entangled sample (stainless steel, 127µm diameter) as a function of the volume fraction In the case of stainless steel wire, a follow-up of the deformation was performed for two diameters (Figure 6 and 7). First, we can notice, for both diameters, that the distribution of the wire through the volume of the sample is heterogeneous. The local density seems higher at the contact with the mold and the pistons and smaller in the center. The increase of the volume fraction does not appear to radically change this heterogeneous distribution. Nevertheless, the sample with the smaller diameter (127µm) seems slightly more homogeneous than the one with a 200µm diameter. This was expected since smaller wire diameter means smaller curvature radius and thus easier arrangement of the wire for the same mold radius. Figure 8: Evolution of the cross section of a monofilament entangled sample (pearlitic steel, 120µm diameter) as a function of the volume fraction. The volume fractions are different from the one for the stainless steel because of technical limitations. In the case of the pearlitic steel (Figure 6-B), we can notice that the profile is even more heterogeneous. Due to the very high yield strength of the wire, the curvature radius is very large and the wire ends up on the outer volume of the mold. Qualitatively, we can already notice the heterogeneous nature of monofilament entangled materials submitted to a constrained compression test, as well as the influence of the diameter and yield strength of the constitutive wire. 37
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