Influence of temperature on the compression performance and failure modes of PETG-CF honeycomb structures

Current understanding of carbon fiber-reinforced PETG (PETG-CF) honeycomb structures remains limited, with their mechanical properties and failure mechanisms insufficiently characterized across a wide operational temperature range from −20°C to 65°C. This study addresses this knowledge gap by systematically investigating the quasi-static compressive response of regular hexagonal PETG-CF honeycombs. A combined approach of experimental testing and thermo-mechanically coupled numerical simulations was employed. Experimental characterization, complemented by fracture surface analysis using scanning electron microscopy (SEM), revealed pronounced temperature-dependent effects on compressive modulus, specific energy absorption (SEA), and failure modes. The results indicate a clear trend, the compressive modulus decreases from 47.76 MPa at −20°C to 39.84 MPa at 65°C, while the SEA declines by 52.4%, from 1.03 MJ/m 3 to 0.49 MJ/m 3 . Failure modes exhibit strong temperature dependence. Brittle fracture, characterized by matrix cracking and fiber breakage, dominates at low temperatures (−20°C, −10°C, 0°C). At 25°C, a brittle-to-ductile transition occurs, whereas plastic buckling and interfacial debonding become the primary failure mechanisms at higher temperatures (45°C and 65°C). Finite element analysis further elucidates the role of geometric stress concentration zones as consistent initiation sites for failure. Importantly, the evolution of failure is governed by the temperature-dependent plastic deformation capability of the PETG-CF matrix. This work establishes a fundamental link between temperature and the progression from microscopic damage to macroscopic failure, providing a theoretical foundation for the design of lightweight structures operating across broad temperature ranges.