Experimental and Numerical Investigation on the High‐Temperature Creep Behavior of Aramid Honeycomb Cores: Constitutive Model Development and Geometric Characteristics Effects

ABSTRACT Aramid honeycomb cores are susceptible to irreversible deformation during secondary bonding at 120°C and 180°C, resulting in geometric deviations in sandwich structures that exceed tolerance limits. To elucidate the underlying deformation mechanisms, a planar compression creep assembly was designed to replicate the thermomechanical loading conditions experienced by the honeycomb core during processing. Experimental results demonstrate that irreversible deformation is primarily driven by creep behavior, characterized by the formation of plastic hinges. Building on these findings, time‐dependent creep curves were fitted in MATLAB, and the Findley power‐law was identified as the optimal creep model. To generalize the constitutive model, a temperature‐dependent Enhanced Findley Model that incorporates the geometric characteristics of the honeycomb core was developed, achieving a fitting accuracy above 98%. A CREEP subroutine was subsequently developed in FORTRAN 77 and integrated into ABAQUS. Furthermore, the influence of geometric characteristics on creep behavior was systematically investigated. The results reveal that the hexagonal topology exhibits the highest creep susceptibility, while the triangular topology demonstrates superior creep resistance. Additionally, creep strain increases with wall length, decreases with wall thickness, and shows a nonlinear dependence on variations in the expanding angle.