Announcing The Premiere of The PHD Comics MOVIE!!!!!!!!

Dr. Jorge Cham creator of the popular webcomic “Piled Higher and Deeper”
(PHD Comics) has partnered with Theater Arts at the California Institute
of Technology (TACIT) to create a live action film! The movie is based on
PHD Comics and brought to you by Caltech students, staff, and faculty!
“The PHD Movie” was directed by Vahe Gabuchian, a Ph.D. Candidate in
Aeronautics, produced by Meg Rosenburg, a Ph.D. candidate in Planetary
Science, and written by Dr. Cham himself. It is already scheduled to

DOI: 10.1007/s00033-011-0136-1

Snap-through actuation of thick-wall electroactive balloons

Stephan Rudykh (a), (c), Kaushik Bhattacharya  (c) and Gal deBotton (a), (b)

(a) Department of Mechanical Engineering, Ben-Gurion University, 84105 Beer-Sheva, Israel

(b) Department of Biomedical Engineering, Ben-Gurion University, 84105 Beer-Sheva, Israel

(c) Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125, United States

  
  
Abstract

Solution to the problem of a spherical balloon made out of an electroactive polymer which is subjected to coupled mechanical and electrical excitations is determined. It is found that for certain material behaviors instabilities that correspond to abrupt changes in the balloon size can be triggered. This can be exploited to electrically control different actuation cycles as well as to use the balloon as a micro-pump.

DOI:10.1016/j.ijnonlinmec.2011.05.006

http://www.springerlink.com/content/wx185g5301300521/fulltext.pdf

Macroscopic instabilities of fiber reinforced composites undergoing large deformations are studied. Analytical predictions for the onset of instability are determined by application of a new variational estimate for the behavior of hyperelastic composites. The resulting, closed-form expressions, are compared with corresponding predictions of finite element simulations. The simulations are performed with 3-D models of periodic composites with hexagonal unit cell subjected to compression along the fibers as well as to non-aligned compression. Throughout, the analytical predictions for the failures of neo-Hookean and Gent composites are in agreement with the numerical simulations.

It is found that the critical stretch ratio for Gent composites is close to the one determined for neo-Hookean composites with similar volume fractions and contrasts between the phases properties.

During non-aligned compression the fibers rotate and hence, for some loading directions, the compression along the fibers never reaches the level at which loss of stability may occur.

Hello,

I am looking for a basic book on Bloch wave analysis. (It will be applied in modelling of periodic material). Can you suggest any book or paper for me to focus on?

Thanks,

Stephan