Yang Wei wants to reform attitudes towards research ethics at Zhejiang University and across the country.

Yang Wei has an easy smile and a carefree, even distracted, air — but he takes such a solemn approach to life that his wife sometimes tells him to relax. “I take everything seriously,” he says.

I am currently accepting applications for two Ph.D. students starting in Spring or Fall 2012. The students will join my research group (http://www.colorado.edu/MCEN/people/faculty/xiao.html ) in the Department of Mechanical Engineering at University of Colorado Boulder. 

Huajian Gao, Walter H. Annenberg Professor of Engineering at Brown University,  has been selected to receive the 2011 Charles Russ Richards Memorial Award from the American Society of Mechanical Engineers (ASME) for outstanding achievements in mechanical engineering 20 years or more following graduation. Formal presentation of the award is scheduled to take place during the ASME International Mechanical Engineering Congress and Exposition, to be held in Denver, Colorado, from November 11-17, 2011.

Adhesion has long been an important issue for mechanics and many other disciplines. Its influence spans macro-, micro-, nano- and molecular scales. When size goes down, adhesion plays a more and more significant role. Many important technologies attribute to adhesion, such as transfer printing for advanced microfabrication,  super adhesives inspired by gecko foot hairs, and self-assembly. Adhesion also has strong implications on the behavior of nanomaterials (such as nanotubes and graphenes) and biological system (such as cells). This minisymposium "Mechanics of Adhesion" is to provide a forum of discussion and communication, for researchers working on and interested in adhesion related subjects.

Professors John Rogers and Ares Rosakis were elected to NAE, among the 68 new NAE members. 

John A. Rogers, Lee J. Flory-Founder Chair in Engineering, department of materials science and engineering, University of Illinois, Urbana-Champaign. For novel electronic and optoelectronic devices and systems.

Ares J. Rosakis, Theodore von Kármán Professor of Aeronautics and professor of mechanical engineering, and chair, division of engineering and applied science, California Institute of Technology, Pasadena. For discovery of intersonic rupture, contributions to understanding dynamic failure, and methods to determine stresses in thin-film structures.

Professor Yonggang Huang is selected to receive the 2010 Charles Russ Richards Memorial Award.

The Charles Russ Richards Memorial Award, a joint award of Pi Tau Sigma and ASME, is presented to the engineering graduate who has demonstrated outstanding achievement in mechanical engineering twenty years or more following graduation. Any person who, on July 1 of the year of the award, graduated twenty years or more from the regular engineering program of a recognized college or university shall be eligible for recognition.

Graphene edges, analogous to the structure of nanotubes, can significantly influence the overall electronic and magnetic properties of graphene nanostructures, and thus have become important issues in graphene research, especially for electronic applications. In this recent paper published on PRL, we reported that the free folding of suspended graphene sheets by random mechanical stimulation has preferred folding directions. Among ~100 folded graphene edges examined by electron nanodiffraction, about 1/3 are armchair and 1/3 are zigzag. We explored the energetics of graphene folding by atomic simulation. It is shown that armchair and zigzag edges correspond to two energy minima and thus dominate the graphene folding.

A review paper on stretchable electronics written by Professors John A. Rogers, Takao Someya, and Yonggang Huang was published in a recent issue of Science . This paper gives a nice summary on the recent advances in inorganic and organic stretchable electronics. Materials, structures and mechanics of these systems are discussed. Many attractive applications of stretchable electronics are introduced, such as stretchable silicon circuit, electronic eyeball camera, and flexible LED display. 

Here is the abstract of this review:

In this paper recently feature on the cover of Science Translational Medicine, we report the development of a class of mechanically flexible silicon electronics for multiplexed measurement of signals in an intimate, conformal integrated mode on the dynamic, three-dimensional surfaces of soft tissues in the human body. Mechanics model shows that the strain in the fragile materials, e.g. silicon, is several orders of magnitude smaller than the fracture strain, when wrapped onto the curvilinear cardiac surface.

In this recently published paper on Nanotechnology, we studied the in-surface buckling mechanics of one dimensional nanomaterials on elastomeric substrates.  Simple analytical solutions are obtained for buckling wavelength and amplitude, which can be easily applied to the in-surface buckling of different nanomaterials, such as nanowires and nanotubes.  It is shown that in-surface buckling of nanomaterials has lower energy than out-of-surface buckling, which explains the experimental observance of in-surface buckling of silicon nanowires.  However, single-walled carbon nanotubes (SWNTs) are reported to buckle out-of-surface on PDMS substr

Single-walled carbon nanotubes (SWNTs) possess extraordinary electrical and mechanical properties, with many possible applications in electronics and materials science. Dense, horizonally aligned arrays of linearly configured SWNTs represent perhaps the most attractive and scalable way to implement this class of nanomaterial in practical systems. Recent work shows that templated growth of tubes on certain crystalline substrates (e.g. quartz) yields arrays with the necessary levels of perfection, as demonstrated by the formation of devices and full systems on quartz. To study the alignment (orientation preference) of SWNTs on quartz substrate, we established a mechanics model for the van der Waals interaction between SWNTs and quartz substrate.

Buckling of thin layers or aligned arrays of stiff materials on elastomeric substrates has many important applications, such as stretchable electronics, precision metrology and flexible optoelectronics.  These systems show one common phenomenon, the stiff thin layers buckle normal to the substrate surface (out-of-surface buckling).  By contrast, we recently reported for the first time that silicon nanowires (SiNWs) on elastomeric substrates buckle only within the substrate surface, i.e. in-surface buckling.  Experimental process to obtain buckled SiNWs is described.

Solid mechanician and Caltech Faculty Member Named to American Academy of Arts and Sciences: Caltech professor Ares Rosakis, is among the 210 new fellows elected to the American Academy of Arts and Sciences this year. They join an assembly that was founded in 1780 by John Adams, James Bowdoin, John Hancock, and other scholars to provide practical solutions to pressing issues.

In this recent work, we showed a new design of mechanically flexible and optically semitransparent solar cells with high efficiency. The ultrathin geometry of the microcell together with the neutral plane design enabled the solar cells could be bent to a radius as small as 4.9 mm (the size of a pencil). The position of the silicon neutral plane was given analytically, which provides a criterion for the geometry optimization. The strain in the silicon was shown to be much smaller than the failure strain by both theoretical analysis and finite element simulations. User-definable transparency feature was also obtained by utilization of optical concentrator and sparse layout of microcells. The mechanical flexibility and optical transparency imply it's broad applications on clothes, buildings and cars.  This work was featured on the cover of November, 2008 issue of Nature Materials.

We have studied the scaling of controlled nonlinear buckling processes in materials with dimensions in the molecular range (i.e., ～1 nm) through experimental and theoretical studies of buckling in individual single-wall carbon nanotubes on substrates of poly(dimethylsiloxane). The results show not only the ability to create and manipulate patterns of buckling at these molecular scales, but also, that analytical continuum mechanics theory can explain, quantitatively, all measurable aspects of this system. Inverse calculation applied to measurements of diameterdependent buckling wavelengths yields accurate values of the Young’s moduli of individual SWNTs.

In honor of its two recent National Medal of Science recipients, Jan Achenbach and Tobin Marks, Northwestern University held a National Medal of Science Symposium on May 14.

Achenbach and Marks received their medals at a White House ceremony in July 2007. The medal honors individuals for “pioneering scientific research in a range of fields, including physical, biological, mathematical, social, behavioral and engineering sciences, that enhances our understanding of the world and leads to innovations and technologies that give the United States its global economic edge.”