Students walking along Ho Plaza
Duffield Hall at sunset.
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Two students walking on Engineering Quad towards Duffield

Alan Zehnder

Professor
Associate Dean for Undergraduate Programs
Sibley School of Mechanical and Aerospace Engineering

Biography

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.

Research Interests

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.

Teaching Interests

My undergraduate teaching interests are in engineering mechanics and materials, and engineering mathematics. At the graduate level I teach solid mechanics and fracture mechanics

Selected Publications

  • Jikun Wang, Tianjiao Lia, Fan Cui, Chung-Yuen Hui, Jingjie Yeo, Alan T. Zehnder, ” Metamodeling of Constitutive Model Using Gaussian Process Machine Learning,” Journal of the Mechanics and Physics of Solids, 154,  104532, https://doi.org/10.1016/j.jmps.2021.104532 (2021).
  • Fan Cui, Jikun Wang, Alan Zehnder, Chung-Yuen Hui, ” Effect of Drying on the Viscoelastic Response of a Dual-crosslinked PVA Hydrogel,”   Mechanics of Materials, 160, September 2021, 103984 https://doi.org/10.1016/j.mechmat.2021.103984 (2021).
  • Zezhou Liu, Michael Zakoworotny, Jingyi Guo Alan Zehnder, Chung-Yuen Hui, “Energy release rate of a single edge cracked specimen subjected to large deformation,” International Journal of Fracture, 226, 71-79, (2020). https://doi.org/10.1007/s10704-020-00479-7
  • Aditya Bhaskar, B. Shayak, Richard H. Rand, Alan Zehnder, “Synchronization characteristics of an array of coupled MEMS limit cycle oscillators, “International Journal of Nonlinear Mechanics, 128, 103634 (2021).  https://doi.org/10.1016/j.ijnonlinmec.2020.103634
  • Alan T. Zehnder, Viraj Patel, and T.J. Rose, “Micro-CT Imaging of Fibers in Composite Laminates under High Strain Bending,” Experimental Techniques, 44(5), 531-540 (2020), https://doi.org/10.1007/s40799-020-00374-9
  • Mincong Liu, Jingyi Guo, Zhilong Li, Chung-Yuen Hui and Alan T. Zehnder, “Crack Propagation in a PVA Dual-Crosslink Hydrogel: Crack Tip Fields Measured using Digital Image Correlation,” Mechanics of Materials, 138, 103158, (2019). https://doi.org/10.1016/j.mechmat.2019.103158

See all Publications

Selected Awards and Honors

  • Sia Nemat-Nasser Award and Medal, Society for Experimental Mechanics, 2021
  • Fellow of the Society for Experimental Mechanics (SEM), 2019
  • Dennis G. Shepherd Teaching Award (College of Engineering, Cornell University), 2018
  • 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

Education

  • 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

Websites