Load-bearing stability and fracture behavior of continuous fiber 3D-printed ceramic truss sandwich structures

This study investigates the architecture-dependent load-bearing and progressive fracture behavior of continuous-fiber (CF) 3D-printed ceramic matrix composite (CMC) corrugated-truss sandwich structures under monotonic and short-term cyclic compression. Six different types of CMC sandwich configurations featuring various corrugated truss cores were fabricated. Their load-bearing capacity, deformation characteristics, and fracture behavior were systematically evaluated under monotonic compression, constant-amplitude cyclic loading, and variable-amplitude cyclic loading. The results showed that the CF-reinforced trusses could withstand multiple local failure events. The initial failures occurred mainly as tensile-opening or mixed tensile-opening–shear-sliding fractures in the face sheets or at the face-sheet–member junctions. The continuous fibers remained aligned along the printed load-transfer paths and contributed to the retention of structural load-bearing capacity after local fracture. Under constant-amplitude cyclic loading, all six truss configurations maintained stable load-bearing responses within the tested load range and cycle number. Under variable-amplitude cyclic loading, the hexagonal truss developed progressive irreversible local deformation, while the rhomboidal truss retained substantial load-bearing capacity after local fracture through load redistribution. These room-temperature compression results provide a basis for the structural design of CF 3D-printed ceramic trusses and indicate their potential for lightweight sandwich structures, subject to further validation under representative service conditions.