52. characterizing the collagen structure of armored carapace of the boxfish

Department: Mechanical & Aerospace Engineering
Research Institute Affiliation: CaliBaja Center for Resilient Materials & Systems
Faculty Advisor(s): Joanna M. McKittrick

Primary Student
Name: Sean Nolan Garner
Email: sgarner@ucsd.edu
Phone: 661-575-7399
Grad Year: 2022

Abstract
The carapace of the boxfish (Lactoria cornuta) is comprised of hexagonal dermal scutes made from a compliant protein base and a mineral surface plate. These scutes compensate for the boxfish?s slow swim speeds by offering a strong and flexible armor to protect against predators. The mineral plates interface together in a suture-like structure with an underlying impact resistant collagen structure bridging the plates together. The goal of this project is to further characterize the complex collagen structure found in the boxfish dermis using in-situ scanning electron microscopy (SEM), micro-computed tomography (-CT), in-situ small angle x-ray scattering (SAXS), and nanoindentation mapping. It has been previously shown with tensile, punch, and shear tests that failure usually occurs on the collagen fibers at the interfaces between scutes, as opposed to the sutured mineral interface or the collagen network under the interior of the scutes. Previous SEM characterization of the scutes with the mineral plate removed shows the collagen fibers in an evenly spaced ladder-like orientation. This ladder-like orientation has been further confirmed by the data obtained from in-situ SEM and in-situ small angle x-ray scattering. Utilizing SEM, -CT, and SAXS characterization provides a better 3-dimensional understanding of the complex collagen network and its resultant toughening mechanisms. Moreover, -CT 3-dimensional images demonstrated that the ladder-like orientations are a result of observing a 2D slice of the complicated Bouligand structure. Finite element analyses and further research are being performed to understand how this complex and hierarchical collagen structure optimizes both flexibility and toughness such that we can produce bioinspired designs for impact resistant armors. This work is supported by funding provided by the Multi-University Research Initiative through the Air Force Office of Scientific Research (AFOSR-FA9550-15-1-0009)

Industry Application Area(s)
Aerospace, Defense, Security | Life Sciences/Medical Devices & Instruments | Materials

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