Bending behaviors of carbon fiber composite honeycomb cores with various in-plane stiffness.

[Display omitted] • Carbon fiber composite curved-wall honeycomb was designed to reduce in-plane stiffness. • A modified co-curing method was selected for fabrication process. • The theoretical model and three-dimensional failure mechanism map of carbon fiber composite curved-wall honeycomb is established. • The bending flexibility improved by nearly ten times and is comparable to that of aluminum honeycomb. • The peak bending load per unit mass improved 51.64% after replacing straight wall with semicircular curved wall. Designing curved surfaces with a traditional straight-walled honeycomb is challenging due to its excessive in-plane stiffness, making it prone to fracturing during bending. The research motivation is overcoming the flexibility limitation of conventional straight-wall honeycombs with the new curved-wall design. Moreover, the three-dimensional failure mechanism map based on the theoretical models is expected to contribute to the design of a carbon fiber composite curved-wall honeycomb. This paper outlines the fabrication process using a modified co-curing method. It also includes theoretical models developed to examine the effect of the center angle of curved walls on the honeycomb's in-plane stiffness and bending behavior. In-plane tensile and three-point bending tests were conducted to verify the theoretical modes. Finite element model was created to study the stress distribution and damage degree. The study is also aimed at examining the load-bearing capacity of sandwich beams with curved-wall honeycomb cores. A three-dimensional failure mechanism map shows how the failure modes of sandwich structures are affected by the center angle of the curved walls. The study offers a new approach to designing carbon fiber composite honeycombs with flexible bending deformation and high load-bearing capacity. These honeycombs could potentially be used in lightweight launch-vehicle shell structures. [ABSTRACT FROM AUTHOR]