High temperature mechanical properties of lightweight C/SiC composite pyramidal lattice core sandwich panel

Lattice core sandwich panels, fabricated from metal or resin matrix composites, can not be used under high temperature. Here, we devise a novel pyramidal lattice core sandwich panel fabricated from ceramic matrix C/SiC composite which can be used up to 1600 °C. We evaluate the high temperature mechanical properties through experiments, theoretical analysis, and finite element analysis. Under room temperature, 1200 °C and 1600 °C, the compressive strengths are as high as 12.70, 5.35 and 2.45 MPa, and the modulus are 630, 260 and 120 MPa, respectively. The specific bending strengths are up to 260.7, 168.7 and 152.1MPa/(g·cm3). We also exclusively reveal that with increasing temperature, the critical relative density for the failure models shows significant reduction, indicating service temperature increment enables the original fracture failure to transfer to the buckling of the core bars. Moreover, we develop a finite element analysis model which can well calculate the damage evolution, failure mechanism and models observed in experiments. The failure model under compression is the fracture of the core bars while the bending failure is shear failure of the core bars. These results indicate that the C/SiC sandwich panel integrates high temperature resistance, lightweight characteristic and robust mechanical properties.