I work for an optics company and many of its products contain lenses that are bonded together with a very thin (~0.010mm) UV curing adhesive (Norland Adhesives NOA61 is the most common). Up until recently we have never had any issues with the strength of the bond. However we have recently had a particular design fail during a temperature cycle so I am tasked with looking at why, and how to keep it from happening in the future. The temperature range isn't too scary, -40 to +85C.
(to appear in International Journal of Fracture; Proceedings of the 5th Intl. Symposium on Defect andMaterial Mechanics)
Amit Acharya and Claude Fressengeas
Dielectric elastomer (DE) is a kind of electroactive polymer material,
capable of large deformation up to 380%. However, under conservative
operating conditions, DE is susceptible to instability with a small
deformation due to various modes of failure, including electrical
breakdown, electromechanical instability (EMI), loss of tension and
rupture by stretch. This paper proposes a free energy model in the
thermodynamic system of DE involving thermoelastic strain energy,
electric energy and purely thermal contribution energy to obtain the
stability conditions of all failure modes. The numerical results
indicate that the increase in temperature can markedly contribute to
improving the entropy production, the actuation stress and the critical
(to appear in Quarterly of Applied Mathematics)
by Marshall Slemrod and Amit Acharya
Given an autonomous system of Ordinary Diff erential Equations without an a priori split into slow and fast components, we defi ne a strategy for producing a large class of `slow' variables (constants of fast motion) in a precise sense. The equation of evolution of any such slow variable is deduced. The strategy is to rewrite our system on an in finite dimensional "history" Hilbert space X and defi ne our coarse observation as a functional on X.
I have been reading the book by Prof Anil K Chopra on Structural Dynamics. You might all be aware that Prof Chopra is from University of California Berkeley.
I have been reading the chapter 14, wherein the author talk of reducing the dynamic degrees of freedom using Rayleigh Ritz method.My question is, in commercial FE software , is the reduction of dynamic degrees of freedom practised?
If yes, what are the methods used? IS Rayl;eigh Ritz approiach used?
Kajal
I am looking for a Ph.D. student to work on geometric mechanics of growing bodies (both surface and bulk growth). Candidates with strong math and mechanics backgrounds are encouraged to apply. Interested candidates should email me (arash.yavari [at] ce.gatech.edu) their CV along with the names of three references.
