Alan T.
Zehnder
Associate Professor, Theoretical and Applied Mechanics
317 Kimball Hall, (607)255-9181; atz2@cornell.edu
B.S. 1982 (California at Berkeley); M.S. 1983, Ph.D. 1987 (California
Institute of Technology)
Biography
Zehnder received his doctorate in mechanical engineering with a minor in
materials science from the California Institute of Technology. He stayed
on as a postdoctoral research fellow for one year, and joined the Cornell
faculty in 1988. In 1993 he was the faculty member in residence in Hamburg,
Germany, for the Cornell Engineering Abroad program. He was a Senior Faculty
Fellow at the Naval Surface Warfare Center, Carderock, Maryland in 1998.
He was awarded the 1988 Rudolf Kingslake Medal and Prize from the Society
of Photo-Optical Instrumentation Engineers (now the International Society
for Optical Engineering) for his paper on optical methods in dynamic-fracture
experimentation, which appeared in Optical Engineering. Zehnder
is a member of the American Society of Mechanical Engineers and the Society
for Experimental Mechanics.
Research Interests
My research interests are in solid mechanics, materials, and experimental
techniques. Particular interests include nonlinear and dynamic fracture
mechanics, metal/ceramic interface fracture, fatigue fracture, metal cutting,
nanomechanical oscillators, and fault-propagation folding. Work in my group
is primarily experimental, but with a great deal of finite-element analysis
as well as other forms of analysis to support and interpret the experimental
results.
Past work includes studies of dynamic fracture initiation and growth
in high-strength metals using high-speed photography and high-speed infrared
detector arrays, studies of the mechanics of cracks in thin plate under
tension and bending loads, and studies of metal/ceramic interfacial bond
toughness. As part of the aircraft structural integrity program sponsored
by the National Aeronautics and Space Administration, we studied fatigue
crack growth in thin sheets under tensile and transverse shear loading.
This work included fatigue-crack-growth experiments, theoretical analysis
of the crack-tip stress fields, and nonlinear finite-element simulation
of the test specimen used in the experiments.
Currently, we are continuing to use high-speed infrared detectors to
measure the temperature rise during transient metal cutting. We are
also performing extensive finite element simulations of cutting with the
goal of combining experimental measurements of temperature, cutting forces,
and strain fields to develop appropriate parameters for the simulations.
Working with reseachers from Wayne State University we are applying high
speed thermal imaging to crack tearing with the goal of extracting energy
flow to the crack tip from thermal images. Recently I have also been
working on folding of the earth's crust ahead of a fault. This is
being done via kinematical and finite element simulations. We have
also recently begun a project on high frequency MEMS oscillators.
Current Research Projects
-
Fracture and fatigue in Thin Sheets under Tension and Tearing
-
Other participants: H. Hui and Alberto Zucchini
Thermomechanical Coupling in Metal Cutting, (National Science Foundation)
Other participants: Yogesh Potdar (graduate student) and Xiaomin Deng,
(Univ. of S. Carolina.)
Infrared Imaging for Crack Growth and Conversion of Plastic Work to Thermal
Energy,
Other participants: Kavi Bhalla, (graduate student), Robert Thomas, Skip
Favro, Xiaoyan Han (Wayne State University)
Dynamic Mechanical Properties of Nanoscale Materials, (National
Science Foundation through Cornell Center for Materials Research)
Teaching
Last revised: April 3, 2001