Session: 06-03-02: Advances in Aerospace Structures and Materials-2

Paper Number: 165601

A Systematic Experimental Investigation on Damage Tolerance Enhancement of Conch Shell Inspired Multi-Material Composites 

Characterized by their remarkable impact toughness, conch shells are one of the most impressive body armors that appear in nature. The complex hierarchical architecture and unique material composition of conch shells both contribute to its unique capabilities of deflecting and arresting cracks, resulting in structures with excellent damage tolerance. Through systematic experiments, this research investigates the toughening mechanisms behind conch shells and their applications in biomimetic composites. A 3D biomimetic conch shell prototype was developed and fabricated by multimaterial additive manufacturing. To emulate the unique structure and behavior of conch shells, the biomimetic samples combined materials from two different groups (categorized as "Stiff" and "Soft") and were 3D printed in [0/90/0] and [90/0/90] stacking sequences. 3-point bend tests revealed significantly different groups of mechanical behaviors within the samples. Stiffer samples exhibited brittle fracture with rapid crack propagation prior to failure. In the soft samples, cracks were propagated and deflected along the soft inclusions, enabling excellent toughening mechanisms similar to conch shells. It is evident that the mechanical response of biomimetic materials is guided by both the material properties and the structural design. In order to gain a deeper understanding of the underlying damage tolerance mechanisms in conch shells, parametric studies  were conducted on the following variables: support span length (1 inch/2 inch), misalignment of patterning (high/low), and notch inclusion (yes/no). With the inclusion of a notch, peak load and deformation were greatly reduced in the stiffer samples. In contrast, the softer samples were still capable of withstanding significant deformation before failure, indicating the presence of effective crack deflection mechanisms and reduced notch sensitivity. For samples without notch inclusions, low misalignment patterns generally resulted in structures with higher peak load and deformation. The most notable result was observed for soft samples with a low misalignment pattern. Besides excellent mechanical response, this type demonstrated outstanding damage tolerance characterized by a distributed damage network. The existence of multiple crack propagation pathways and failure zones enabled energy-dissipation mechanisms during loading and allowed the material to withstand significant plastic deformation before failure. The results prove that, by effectively mimicking the conch shell structure, outstanding damage tolerance can be achieved in biomimetic composites. However, this requires incorporating the correct combination of soft and stiff materials and optimizing the structural design for specific applications. The findings of this research lay the groundwork for the development of advanced protective equipment using biomimetic materials.
 

Presenting Author: Muhammed Jawaad Zulqernine Mechanical and Aerospace Engineering, The University of Texas at Arlington

Presenting Author Biography: Muhammed is a Ph.D. student in Mechanical Engineering at The University of Texas at Arlington. His research interest is damage and failure of composite materials.

Authors:

Muhammed Jawaad Zulqernine Mechanical and Aerospace Engineering, The University of Texas at Arlington
Mahatab Bin Rashid West Virginia University
Shiyao Lin Mechanical and Aerospace Engineering, The University of Texas at Arlington