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Understanding the Transition from Positive to Negative Poisson's Ratio Behavior in Cellular Materials and the Potential for Auxeticity in Trabecular Bone

Matheny, Julie C.
http://rave.ohiolink.edu/etdc/view?acc_num=toledo1310140272

Abstract Details

2011, Master of Science in Bioengineering, University of Toledo, Bioengineering.
Negative Poisson's ratio (i.e. auxetic) materials are materials that exhibit lateral expansion under axial tension. Auxetic materials hold promise for practical applications in bioengineering, including sensors, actuators, and energy harvesting devices. It has been reported in the literature that some human trabecular bone is auxetic; however verification of this claim and measurement of the Poisson's ratio of biological materials remains a challenge. The current approach to the design of auxetic materials is based on a select group of known auxetic microstructures. Conventional polyurethane foam, which is widely used to model the three-dimensional scaffold characteristic of trabecular bone, transitions into having auxetic properties when subjected to heat under compression. Through evaluation of polyurethane (PU) foam microstructure using three-dimensional (3D) bone morphometrics and finite element modeling of these conventional and auxetic foam microstructures and the transition process, we present an approach to identify the critical features of auxetic open-cell structures and establish a relationship between microstructure and the onset of auxetic behavior. The results of the finite element model simulating volumetric compression suggest that the auxetic effect is increased with increasing volumetric compression at small strains. A maximum volumetric compression ratio of 1.66 yielded the greatest auxetic effect. Using foams, a two-fold, isometric increase in the trabecular number (Tb.N.) was observed in compressed foam as compared to uncompressed foam and a two-fold isometric decrease in trabecular spacing (Tb.Sp.). Together, these measurements indicate that the dimensional relationship between foam rods did not change during the compression process. The method presented provides a framework through which the potential for auxetic behavior in human cancellous bone can be evaluated and informs the design for auxetic cellular biological materials such as artificial discs and scaffolds.
Lesley Berhan (Committee Chair)
Vijay Goel (Committee Member)
Patricia Relue (Committee Member)
Biomedical Engineering
polyurethane foam; auxetic; negative Poisson's ratio

Recommended Citations

Citations

  • Matheny, J. C. (2011). Understanding the Transition from Positive to Negative Poisson's Ratio Behavior in Cellular Materials and the Potential for Auxeticity in Trabecular Bone [Master's thesis, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1310140272

    APA Style (7th edition)

  • Matheny, Julie. Understanding the Transition from Positive to Negative Poisson's Ratio Behavior in Cellular Materials and the Potential for Auxeticity in Trabecular Bone. 2011. University of Toledo, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1310140272.

    MLA Style (8th edition)

  • Matheny, Julie. "Understanding the Transition from Positive to Negative Poisson's Ratio Behavior in Cellular Materials and the Potential for Auxeticity in Trabecular Bone." Master's thesis, University of Toledo, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1310140272

    Chicago Manual of Style (17th edition)

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© 2011, all rights reserved.
This open access ETD is published by University of Toledo and OhioLINK.