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Symposia Invited Speakers
SYMPOSIUM 2 Dr. Baxevanis has a broad range of interests in the mechanics of
materials, including constitutive modeling, fracture mechanics, damage,
ON THE MECHANICS OF OVERLOAD AND FATIGUE FAILURE IN and micromechanics in active, conventional structural, and composite
SHAPE MEMORY ALLOYS materials. His current research focus is on the fundamental understanding
of the deformation and failure response of shape memory alloys and on
accelerating their development cycle for specific applications.
Theocharis Baxevanis SYMPOSIUM 3
Assistant Professor
Department of Mechanical Engineering
University of Houston
MODAL CHARACTERISTICS OF STRING NETWORKS
Abstract James Gibert
Assistant Professor
Since the discovery of Shape Memory Alloys (SMAs), the SMA industry Purdue University
has been dominated by products for biomedical applications with
geometrically small feature sizes, especially endovascular stents. For Abstract
such products, emphasis is being placed on preventing crack nucleation
rather than controlling crack growth. However, the successful integration of The objective of this work is to investigate the dynamic behavior of string
SMAs into commercial actuation, energy absorption, and vibration damping structures, specifically in terms of their modal frequencies and
applications requires understanding and practice of fracture mechanics corresponding vibration modes. The modal characteristics of the
and fatigue damage-tolerant concepts in SMAs. The development of structures are a function of the geometry of the structure, as well as its
such concepts is rather complex owing to the reversibility of phase material properties, the tension in the individual strings, and boundary
transformation, detwinning and reorientation of martensitic variants, the conditions of the structure. In order to accomplish this goal, we assume
possibility of overload and transformation-induced plastic deformation, and the three-dimensional wave equation describes the dynamic behavior of
the strong thermomechanical coupling. Large-scale phase transformation an individual string in the network. A Chebyshev collocation scheme is
under actuation loading paths, i.e., combined thermomechanical loading, used to discretize the partial differential equation. This discretized
and the associated configuration dependence complicate the failure equation is used to form a generalized eigenvalue problem with
response even further and question the applicability of single parameter appropriate to boundary conditions. The approach is validated by
fracture mechanics theories. In this talk, the existing knowledge base on comparing the predictions of the present model obtained with analytical
the mechanics of failure of SMAs under mechanical loading will be briefly solutions from known simple geometric configurations. The approach is
reviewed and recent developments in actuation-induced SMA overload extended to modeling geometrically complex web-like structures and
and fatigue failure will be presented along with deficiencies of the classical examines the effect of tension and boundary on the modal behavior of the
elastic-plastic fracture mechanics theories and standards to treat the network. Results indicate that these structures are characterized by being
observed response and possible remedies to overcome those deficiencies. modally dense, having repeated modal frequencies, and 1:2 and 1:3
proportionality between modal frequencies. It is envisioned that this
Biography modeling effort will aid in the study of internal resonance interactions and
possible saturation phenomenon in these structural systems and inspire
Dr. Theocharis Baxevanis received his Ph.D. in Civil Engineering in 2003 new concepts in adaptive string networks to avoid unwanted nonlinear
from the Aristotle University of Thessaloniki, Greece. Currently, he resides resonant interaction or to design networks structures that absorb, localize,
in Houston, Texas. Dr. Baxevanis is an assistant professor in the Mechanical or divert vibrational energy.
Engineering Department at the University of Texas. Previously, he worked
as a TEES research assistant professor in the Aerospace Engineering
Department at Texas A&M University and as director of operations in the
Center for Intelligent and Multifunctional Materials and Structures (CIMMS).
He also taught at the University of Crete, Greece, in the Department of
Applied Mathematics from 2005 to 2010 and worked as a researcher
in Ecole Centrale de Nantes, France, in 2004 and in SINTEF Petroleum,
Norway, in 2003.
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