Co-authors​ :

 Muhammad Khizer Ali KHAN (UNITED ARAB EMIRATES), Kamran A. KHAN (UNITED ARAB EMIRATES), Wesley.J. CANTWELL  

Cellular structures are known for their outstanding mechanical properties such as light weight, high strength, energy absorption, and vibration reduction. These properties make cellular structure (CS) attractive for many engineering applications especially in the fields of aerospace, bio-medical and automation. Cellular-filled structures, in particular, are popular due to their excellent energy dissipation characteristics in mechanical absorbers. Recently, the progress of novel cellular designs has been accelerated by the advances in additive manufacturing (AM) as it has allowed the rapid manufacturing and testing of computationally optimized, complex geometries. Low relative density (RD) CSs are characterized by thin walls and slender members. Hence, the ability to create lightweight and crashworthy architected CS is a convoluted task as these two properties are mutually exclusive. Inspiration is drawn from the unique materials and structures present in nature, such as in the elytra of a beetle forewing. The microstructure of elytra contains an irregular honeycomb structure having hollow columns that makes it lightweight and rigid.

In this study, the energy-absorbing characteristics of an additively manufactured (AM) composite honeycomb core embedded with circular tubes has been investigated. The specific energy absorption (SEA) and failure mechanism of plain 3D printed honeycomb is utilized to enhance the performance of reinforced honeycomb structures. The honeycomb filled with circular tubes (HFCT) structure is manufactured through Material extrusion (MEX) process using Polyamide (PA) honeycomb as base structure reinforced with composite circular tubes. Honeycomb models with different tube filling modes are studied, including the mimicable porous structure of beetle forewing, to observe the influence of tube patterns on HFCT structures performance. The energy-absorbing characteristics and modes-of-failure are investigated. Preliminary results show that the additively manufactured composite circular tubes in honeycomb structure greatly enhanced the energy-absorption properties of the core structure. Glass / carbon reinforced material used for circular tubes are high-performance and qualified for engineering applications. This multi-material approach presents an efficient design choice for tunable energy absorption devices. The ease in the fabrication of tube-reinforced honeycombs through AM, coupled with exceptional mechanical properties provides promising avenues for its use in extreme conditions.