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 currently serves as Associate Dean for Undergraduate Programs and has 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 polymers and matrix composites.
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. Recent work focuses on the behavior of coupled systems of nano-scale oscillators.
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 their strength.
Composite laminated are well known for their high specific strength and stiffness. Recent work focuses on damage and damage tolerance of sandwich structures and degradation of polyimides exposed to high temperature and moisture.
Please see Zehnder's group website for additional information and links to publications.
My undergraduate teaching interests are in engineering mechanics and materials, and engineering mathematics. At the graduate level I teach solid mechanics and fracture mechanics
- Mincong Liu, Jingyi Guo, Chung-Yuen Hui, Costantino Creton, Tetsuhara Narita, and Alan Zehnder. 2018. "Time-Temperature Equivalence in a PVA Dual Cross-Link Self-Healing Hydrogel." Journal of Rheology 62: 991.
- Jingyi Guo, Mincong Liu, Alan T. Zehnder, Jingwen Zhao, Tetsuhara Narita, Costantino Creton, and Chung-Yuen Hui. 2018. "Fracture mechanics of a self-healing hydrogel with covalent and physical cross-links: A numerical study." Journal of the Mechanics and Physics of Solids 120: 79-95.
- Yi Xu and Alan Zehnder. 2017. "Pressure, Hydrolytic Degradation and Plasticization Drive High Temperature Blistering Failure in Wet Polyimides." Extreme Mechanics Letters 16C: 49-55.
- Scott Grutzik, Erik Milosevic, Brad Boyce and Alan Zehnder. 2015. "Oxide driven strength evolution of silicon surfaces." Journal of Applied Physics 118 (19): 195304.
- Benjamin Hasseldine, Alan Zehnder, Bryan Keating, Abhendra Singh and Barry Davidson. 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.
- David B. Blocher, Richard H. Rand and Alan T. Zehnder. 2013. "Entrainment of Micromechanical Limit Cycle Oscillators in the Presence of Frequency Instability." Journal of Microelectromechanical Systems 22 (4): 835-845.
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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
- B.S. (Mechanical Engineering), University of California- Berkeley, 1982
- M.S. (Mechanical Engineering), California Institute of Technology, 1983
- Ph.D. (Mechanical Engineering), California Institute of Technology, 1987