Fig.6 Fracture plane and fracture surface of specimens (XY view)
subjected to compression loading along Y-direction (a) Buckling of
vertical struts in cubic regular; Shear band like failure in (b) cubic
irregular (c) star regular (d) star irregular (e) cross regular (f)
cross irregular; (g) failure at various locations in trabecular
structures (h) SEM image indicated the formation of shear dimples at the
fracture surface
The stress-strain curves for cross regular and cross irregular are
completely different from the other topologies and overlap on each
other. It consists of a linear region followed by a flat and long
plateau which is due to the absence of struts in the vertical
directions. They have the lowest stress values compared to all the other
structures. The failure of the specimen took place at the junctions and
experienced a shear band formation as shown in Fig. 6e and 6f52–54. The stress-strain curve of the trabecular
structures share some properties of all kinds of topologies. It consists
of a long plateau similar to the cross structures while the maximum
stress value is between cubic irregular and star regular structures. The
stress-strain curves clearly indicate that cubic regular samples exhibit
an ideal stretching dominated behavior and cross regular and cross
irregular samples exhibit an ideal bending dominated behavior.
The cyclic stress- strain curves shown in Fig.5b clearly indicate that
the slope of the curve increases after the first loading cycle. This
increase in stiffness after the first cycle can be due to the compaction
of internal defects and plasticization at junctions which rise the
overall stiffness. The specimens achieve stabilization already from the
first loading cycle irrespective of the cell topology.
Table 2 Young’s Modulus and strength values