Accession Number : ADA623083


Title :   Uncovering and Validating Toughening Mechanisms in High Performance Composites


Descriptive Note : Final rept. 15 May 2012-14 May 2015


Corporate Author : CALIFORNIA UNIV REGENTS RIVERSIDE


Personal Author(s) : Kisailus, David ; Zavattieri, Pablo


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a623083.pdf


Report Date : 17 Sep 2015


Pagination or Media Count : 90


Abstract : The research goal of this project is to study and understand the structure-function relationships in damage-tolerant impact/shockresistant stomatopod dactyl club while addressing the ongoing quest to develop the new generation of scalable high-performance biologically-inspired multifunctional materials. Our ultrastructural investigations have identified that within this multi-regional composite structure, specific regions play very specific roles. We uncovered structural details from the striated region, which exists on the sides of the club. Unidirectional mineralized fibers in this region wrap circumferentially around the club, keeping it under compression during impact and preventing crack growth. To confirm this, we produced new models at multiple length scales and across length scales to show the effects of this outer layer. We compared this to the spearing dactyl of another species of mantis, in which this striated region is located on all sides (supporting flexural loads). We also observed a unique structure within the impact region of the dactyl. Specifically, the helicoidal structure previously identified in the periodic region extended into the impact region with a change in periodicity and forming a herringbone-like structure based on compression of this helicoid. Evidence is provided for the effects of this herringbone structure, which in combination with an outer dense particulate apatite layer, enhances stress redistribution under compressive loading. Within the periodic region, which contains the helicoidal structure, we observed that the periodicity enables not only crack twisting, which toughens the club, but also shear wave filtering, as confirmed using analytical models.


Descriptors :   *BIOMATERIALS , *COMPOSITE MATERIALS , *CRACK PROPAGATION , *SHELLFISH , *TOUGHNESS , BIOMIMETICS , COMPOSITE STRUCTURES , COMPRESSION , COMPRESSIVE PROPERTIES , ELASTIC WAVES , FIBERS , FLEXURAL PROPERTIES , HYDRODYNAMICS , LAYERS , MATHEMATICAL MODELS , MULTIPURPOSE , PERFORMANCE(ENGINEERING) , SHEAR PROPERTIES , SHOCK(MECHANICS) , STRESSES , STRUCTURAL PROPERTIES , UNIDIRECTIONAL , WINDING


Subject Categories : Laminates and Composite Materials
      Mechanics
      Biomedical Instrumentation and Bioengineering


Distribution Statement : APPROVED FOR PUBLIC RELEASE