Abstracts - Conference Planning and Management - Iowa State ...

Influence of Fiber Dissolution and Reassembly on Axial Stratch and Torsion of a
Fiber Reinforced Hyperelastic Cylinder
Alan Wineman
University of Michigan
Department of Mechanical Engineering, Ann Arbor, 48104, US
Phone: 734-936-0411, Email: lardan@umich.edu
Thomas J. Pence
Michigan State University, East Lansing, MI
Alan Wineman
University of Michigan, Ann Arbor, MI
Abstract:
The large deformation mechanical response of materials in which elastic fibers are embedded in an
elastic matrix can be modeled in the context of anisotropic hyperelasticity, where the fibrous structure
is homogenized and represented by different properties in certain directions. The elastic response of
such materials can be considered as arising from a single microstructural mechanism during the entire
range of response, namely the distortion of macromolecules in the matrix or in the molecular structure
of the fibers. In previous work, the authors have developed a theory in which new microstructural
events occur during the response of the fibers. In this theory, fibers undergo dissolution as a result of
increasing elongation and then reassemble in a direction defined as part of the model. The case where
the fibers reassemble in the direction of maximum principal stretch of the matrix was considered.
This model was previously illustrated for a material having fibers in the reference configuration that are
all aligned in a common direction, and subjected to either homogeneous uniaxial extension or simple
shear. The present work studies the implications of the model during the non-homogeneous
deformation of axial stretch and torsion of a circular solid cylinder composed of an isotropic matrix and
families of helically wound fibers. It is shown that the process of fiber dissolution and reassembly
produces complex morphological changes in the fibrous structure and hence, in the response of the
cylinder. The case of a single family of fibers initially aligned axially is studied in detail. It is shown
that the cylinder has an inner core of original material and an outer layer of material in which the fibers
have undergone dissolution and reassembly. The interface between these regions can move radially
inward as axial stretch and/or twist increase. Gradual reassembly of the fibers with increasing stretch
and twist changes their contributions to the torque and axial force and their helical orientation.
Different sequences of axial stretch and twist result in different morphologies in the fibrous structure.
103 ABSTRACTS