An effective bead-spring model combining the advantages of large time steps of traditional bead-rod models and computational rigor of traditional bead-spring models is proposed to simulate the dynamic behaviors of flexible polymer chains with arbitrary longitudinal stiffness. The proposed model can be used to simulate many types of polymer chains or networks with different chain elasticity via a unified integration scheme with reasonably large time steps. The paper can be found at http://dx.doi.org/10.1016/j.jcp.2007.11.012

Variational theory of elasticity is surveyed in the context of mathematical logic in the present paper titled "Variational Theory: Variable-independence and Consistency" . The problem of variable-independence of variational principles raised by Professor Chien Wei-zang is discussed.

 Hi Everybody, Im new to iMechanica. I must admit If I knew of it earlier it could have changed so many things in my life :). Im really glad to be here now. For a start I would like to ask if anyone has any links /sources to this book. I simply cant find it. Ive checked Amazon etc etc. Please help me find this book

"HELICOPTERS: CALCULATION AND DESIGN. VIBRATIONS AND DYNAMIC STABILITY "(Mil, M. L. ; Nekrasov, A. V. ; Braveman, A. S. ; Grodko, L. N. ; Leikand, M.) 1968.

Rgds.

Dominic.

Can we map the eastic modulus of a and c domians? Can we mechanically switch the domains and let them function as nanoactuators and sensors?

Hello! 

As a student who has spent a lot of time studying cohesive zone models in fracture mechanics, I have several questions that have bothered me over the past year or so, and I have not been able to find suitable answers to them. I am limiting myself here to questions related to the traction-separation law, which invariably forms the basis of CZM as it is implemented today. I am raising these questions in the hope that I can receive some response here, even if it means my question is invalid (as I suspect a few may be).  So here is my list:

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Fascinating paper. Congrats to Wei, Xuanhe, and Zhigang. Nice to see a simple and an elegant model together with an intuitively appealing physical interpretation of the bifurcation phenomenon in gels. It woud be interesting to see the time evolution of the drying process and the orientation (theta) of the nano wires.  

A polymer network can imbibe water from environment and swell to an equilibrium state. If the equilibrium is reached when the network is subject to external mechanical constraint, the deformation of the network is typically anisotropic, and the concentration of water inhomogeneous.  Such an equilibrium state in a network constrained by a hard core is modeled here with a nonlinear differential equation.  The presence of the hard core markedly reduces the concentration of water near the interface and causes high stresses.

Hydrogels have enormous potential for making adaptive structures in response to diverse stimuli.  In a structure demonstrated recently, for example, nanoscale rods of silicon were embedded vertically in a swollen hydrogel, and the rods tilted by a large angle in response to a drying environment (Sidorenko, et al., Science 315, 487, 2007).  Here we describe a model to show that this behavior corresponds to a bifurcation at a critical humidity, analogous to a phase transition of the second kind.