This paper investigates experimentally and numerically the influence of geometry and loading conditions on the fracture response of rock materials. Seven different test samples namely “Edge-Notched-Disc-Bend (ENDB), Semi-Circular-Bend (SCB), Three-Point-Bend-Inclined-Crack (TPB-IC), Single-Edge-Notched-Bending (SENB), Asymmetric-Three-Point-Bend (ATPB), Edge-Notched-Disc-Compression (ENDC) and Double-Notched-Disc-Compression (DNDC)” made of a marble rock were manufactured and tested under bending and compressive loading conditions. The results showed that the failure loads of all samples increase with the change of pure mode I to pure mode III. However, the corresponding fracture toughness values of ENDB, SCB, TPB-IC, SENB and ATPB specimens decreased, while the ENDC and DNDC samples experienced an increase in the fracture toughness. Among the studied specimens, only the ENDB, ENDC and DNDC samples presented pure mode III with KIIIc/KIc ratio ranging from 0.735 for the ENDB specimen to 2.076 for the DNDC sample. The highest mode-I fracture toughness among all the studied specimens was obtained for the SENB and TPB-IC samples, with a value of 1.54 MPa m0.5, while the lowest value was obtained for the DNDC specimen with a value of 1.21 MPa m0.5. The sign and the magnitude of T-stress considerably depended on the loading condition and geometry of the specimens. The crack trajectories of all specimens under study were also investigated.

In this paper, the edgewise and flatwise compressive behaviour of an innovative sandwich panel, mainly developed for quick assembly of post-disaster housing as well as load bearing panels for pre-fabricated modular construction and semi-permanent buildings, is investigated experimentally and by finite element modelling. The panel is composed of two 3-D high-density polyethylene (HDPE) sheets as the skins, filled with high-density Polyurethane (PU) foam as the core. HDPE sheets manufactured with a studded surface considerably enhance the stress distribution and buckling performance of the sandwich panel. Material characterisation tests and flatwise compression and edgewise compression experiments were performed in accordance with ASTM standards to evaluate the compressive strength and the load-carrying behaviour of the sandwich panels. A finite element analysis and validation were also conducted to model the compressive behaviour of sandwich structures. Results demonstrate that the developed sandwich panel exhibits very good compressive performance.