T. Watanabe, T.Gotoh

The International Conference on Computational & Experimental Engineering and Sciences, Vol.18, No.3, pp. 91-92, 2011, DOI:10.3970/icces.2011.018.091

Abstract The effects of polymer additives on decaying isotropic turbulence were numerically investigated using a hybrid approach. The approach consisted of a Brownian dynamics simulation with an enormous number of dumbbells and a turbulence DNS with large-scale parallel computations. A reduction of the energy dissipation rate and modification of the kinetic energy spectrum were observed when the reactions of the polymers were incorporated into the fluid motion. We found that results with few polymers and large replicas could approximate those with many polymers and smaller replicas as far as the large-scale statistics were concerned. More >

Leela Rakesh¹, Anja Mueller², Pratik Chhetri¹

FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.2, pp. 179-202, 2010, DOI:10.3970/fdmp.2010.006.179

Abstract A new material for proton conducting membrane with a higher proton transport but reduced water transport is being developed. The new material optimizes proton channel formation, this reducing water transport at the same time. Different proton transporting groups along with different gas flowing channels are examined as well. To meet the goals we design, synthesize, and simulate various proton transporting groups using MD techniques for faster optimization, which in turn helps to synthesize and test only promising structures in the laboratory. At the same time, computer modeling is used to improve the fuel cell system More >

M. Vogler¹, G. Ernst¹, R. Rolfes¹

CMC-Computers, Materials & Continua, Vol.16, No.1, pp. 25-50, 2010, DOI:10.3970/cmc.2010.016.025

Abstract In this article, a constitutive formulation of a transversely-isotropic material and failure model for fiber-reinforced polymers is presented comprising pre-failure material nonlinearities, a novel invariant based quadratic failure criterion (IQC) as well as post failure material softening. The failure surface of the IQ criterion is assumed to take the influence of triaxiality on fracture into account. Further, a distinction between fiber failure and inter-fiber failure is conducted. Material softening is governed by a fracture energy formulation and the introduction of an internal length. The constitutive model is implemented into a programming user interface of the More >

Rama Bansil¹, Minghai Li¹, Yongsheng Liu¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.13, No.4, pp. 75-76, 2009, DOI:10.3970/icces.2009.013.075

Abstract Block copolymers are known to form micelles of different shapes in selective solvents that preferentially dissolve one of the constituent blocks. These micellar fluids exhibit various ordered and disordered phases. To gain microscopic insight into the mechanisms involved in the transformation between different phases we use synchrotron-based time-resolved small angle x-ray scattering (SAXS) and coarse-grained discrete Brownian Dynamics simulations. In this talk I will focus on the kinetics of the transformation from the hexagonal packed cylinder (HEX) phase to cubic phases (FCC or BCC). SAXS data was interpreted with a geometrical model for the transformation… More >

J.A.Ferreira^1,2, P. de Oliveira², P. da Silva³, D. M. G. Comissiong⁴

CMC-Computers, Materials & Continua, Vol.13, No.1, pp. 17-48, 2009, DOI:10.3970/cmc.2009.013.017

Abstract A phenomenological formulation is adopted to investigate desorption in polymers. The speed of the front is studied and the well-posedness of the general model is analyzed. Numerical simulations illustrating the dynamics of the desorption process described by the proposed model are included. More >

M. Uchida¹, N. Tada¹, Y. Tomita²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.6, No.2, pp. 91-98, 2008, DOI:10.3970/icces.2008.006.091

Abstract Micro- to mesoscopic deformation behavior of semi-crystalline polymer with randomly distributed rubber particles is evaluated by numerical simulation. In this model, dimension of mesostructure is identified by volume fraction of interface region around the rubber particles. The effects of strain rate and size of mesostructure on macroscopic stress-strain relation and strain distribution in mesoscopic area are discussed. In the earlier stage of deformation, the slope of stress-strain relation changes by rubber particle size while stress in the following deformation is mainly affected by the tensile strain rate. The anisotropic deformation in lamellar oriented interface region More >

M. Kröger¹, M. Müller², J. Nievergelt²

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.5, pp. 559-570, 2003, DOI:10.3970/cmes.2003.004.559

Abstract We present a novel method for generating starting polymer structures for molecular simulations in the dense phase. The work describes the ingredients of an algorithm for the creation of large, dense or diluted amorphous polymeric systems close to equilibrium and provides measures for its quality. The model systems are made of semiflexible (wormlike) repulsive multibead chains. The key feature of the method is its efficiency, in particular for large systems, while approaching given local and global chain characteristics. Its output has been proven to serve as an excellent basis for subsequent off-lattice molecular dynamics computer More >