In-plane mechanical behavior design of novel re-entrant and hexagonal combined honeycombs

A novel honeycomb structure, termed re-entrant combined hexagonal honeycomb-Type X-theta (RECHH), has been introduced and explored by integrating re-entrant hexagonal and hexagonal honeycombs. Utilizing Abaqus/ Explicit, a finite element numerical model was constructed, verified for accuracy, and subjected to a series of inplane impact investigations. Initially, the in-plane mechanical characteristics of two novel honeycomb configurations, combining re-entrant hexagonal and hexagonal subunits, were compared. Results indicate that RECHHType I-150 degrees exhibits a 49.06 % increase in specific energy absorption (SEA) compared to RECHH-Type I-180 degrees, while RECHH-Type II-160 degrees shows a 45.55 % increase in SEA compared to RECHH-Type II-120 degrees. Moreover, RECHH-Type II-theta demonstrates superior energy absorption compared to RECHH-Type I-theta, with RECHH-Type II160 degrees displaying a 35.66 % SEA increase compared to RECHH-Type I-160 degrees, and RECHH-Type II-130 degrees showing a 10.27 % SEA increase compared to RECHH-Type I-130 degrees. Subsequently, a parameterization study was conducted on RECHH-Type X-150 degrees, exploring various combinations of l0. Mechanical analysis revealed optimal properties at a specific l0 value. Finally, the impacts of wall thickness and velocity on RECHHs were examined. Appropriately increasing wall thickness was found to enhance the structure's impact resistance. The design of reentrant combined hexagonal honeycombs offers practical insights for improving the in-plane mechanical characteristics of honeycomb structures.