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