Alan Taylor Zehnder
Alan 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 visiting Professor at Caltech in the 1996-97 academic year. In summer of 1998 he served as a Senior Faculty Fellow at the Naval Surface Warfare Center in Carderock, Maryland. In 2004 he was a Guest Professor at the Vienna University of Technology. He also served as Associate Dean for Diversity and Faculty Development in the College of Engineering. Zehnder is a member of the American Society of Mechanical Engineers, and the Society for Experiment Mechanics.
Zehnder's research focuses on the fracture of nanoscale systems, nonlinear dynamics of nanomechanical oscillators, damage tolerance of polymer matrix composite materials and wind energy.
Nanoscale systems show surprising effects due to their small size, low damping, interaction with light and other effects. A rich range of behaviors such as sub and super-harmonic entrainment and wide tunability have been discovered in nano-scale beams undergoing CW laser driven limit cycle oscillations.
Nanoscale structures can have strengths close to the theoretical strength of the material. In such structures the only "defect" is often roughness or oxidation on the surface. Research is underway to fully explore the effects of surfaces on the strength of nano-scale systems and to design tactics for improving strength.
Composite laminate sandwich panels are well known for their high specific strength and stiffness. However a concern is that low energy impact may compromise strength. An integrated experimental and numerical study is underway to provide design guidelines and predictive models for assessing the damage resistance and tolerance of sandwich structures.
Please see Zehnder's group website for additional information and links to publications.
I have a broad range of teaching interests in undergraduate mechanics, and engineering mathematics. At the graduate level I teach solid mechanics, fracture mechanics and experimental mechanics.
- 2015. "Oxide driven strength evolution of silicon surfaces." Journal of Applied Physics 118 (19): 195304-195304. .
- 2013. "Accurate spring constant calibration for very stiff atomic force microscopy cantilevers.." Rev Sci Instrum 84 (11): 113706. .
- 2013. "Entrainment of Micromechanical Limit Cycle Oscillators in the Presence of Frequency Instability." Journal of Microelectromechanical Systems 22 (4): 835-845. .
- 2016. "Compressive strength of aluminum honeycomb core sandwich panels with thick carbon-epoxy facesheets subjected to barely visible indentation damage." Journal of Composite Materials 50 (3): 387-402. .
- 2014. "Compressive strength of honeycomb-stiffened graphite/epoxy sandwich panels with barely-visible indentation damage." Journal of Composite Materials 48 (20): 2455-2471. .
Selected Awards and Honors
- Fellow (American Society of Mechanical Engineers) 2013
- Rudolf Kingslake Medal and Prize (Society of Photographic Instrumentation Engineers) 1988
- Charles Lee Powell Fellow 1985
- TRW Advanced Technologies Fellow 1984
- BS (Mechanical Engineering), University of California- Berkeley, 1982
- MS (Mechanical Engineering), California Institute of Technology, 1983
- Ph D (Mechanical Engineering), California Institute of Technology, 1987