Fig.5 Compressive stress-strain curves of all specimens (a) Monotonic loading condition (b) Cyclic loading condition
This is further confirmed by the fracture plane images as shown in Fig. 6a. The cubic irregular structure haa a well-defined and longer plateau compared to the cubic regular structure. This is due to the presence of inclined struts from the displaced nodes. This irregularity decreases the maximum stress that can be sustained by the structure but avoids the sudden failure of regular cubic structures. The fracture plane shown in Fig. 6b indicates a failure plane similar to a shearing band. The star-based topology structure has a plateau region similar to that of cubic irregular structures. The presence of struts in the oblique directions along with the vertical struts decreases the maximum stress that can be sustained when compared to the cubic regular structures which had struts in the vertical direction. However, the oblique struts assist in bearing the load once the vertical strut fails. While considering the star regular and star irregular stress-strain curves, the presence of irregularity has a clear effect on the stress sustained by the structures while the length of the plateau region is unaffected. It is seen from Fig.6c and 6d that the vertical struts fail, but the failure happens along a 45ยบ shear plane.