In-situ AFM Experiments with Discontinuous DIC Applied to Damage Identification in Biomaterials

D. Grégoire, O. Loh, A. Juster, H. D. Espinosa

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Natural materials (e. g. nacre, bone, and spider silk) exhibit unique and outstanding mechanical properties. This performance is due to highly evolved hierarchical designs. Building a comprehensive understanding of the multi-scale mechanisms that enable this performance represents a critical step toward realizing strong and tough bio-inspired materials. This paper details a multi-scale experimental investigation into the toughening mechanisms in natural nacre. By applying extended digital image correlation and other image processing techniques, quantitative information is extracted from otherwise prodominantly qualitative experiments. In situ three point bending fracture tests are performed to identify and quantify the toughening mechanisms involved during the fracture of natural nacre across multiple length scales. At the macro and micro scales, fracture tests performed in situ with a macro lens and optical microscope enable observation of spreading of damage outward from the crack tip. This spreading is quantified using an iso-contour technique to assess material toughness. At the nanoscale, fracture tests are performed in situ an atomic force microscope to link the larger-scale damage spreading to sliding within the tablet-based microstructure. To quantify the magnitude of sliding and its distribution, images from the in situ AFM fracture tests are analyzed using new algorithms based on digital image correlation techniques which allow for discontinuous displacement fields. Ultimately, this comprehensive methodology provides a framework for broad experimental investigations into the failure mechanisms of bio- and bio-inspired materials.

Original languageEnglish (US)
Pages (from-to)591-607
Number of pages17
JournalExperimental Mechanics
Volume51
Issue number4
DOIs
StatePublished - Apr 2011

Keywords

  • Atomic force microscopy
  • Digital image correlation
  • Fracture and damage
  • Image processing
  • Multiscale in situ experiments
  • Nanocomposite
  • Natural nacre

ASJC Scopus subject areas

  • Aerospace Engineering
  • Mechanics of Materials
  • Mechanical Engineering

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