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  • RPI SCOREC - Technical Reports
    study to what extent the reptation of polymers not in direct contact with fillers is modified with respect to the neat material To this end two systems are considered A regular filled material in which the filler polymer affinity is controlled and a system in which the beads in contact with the filler at the beginning of the production phase of the simulation are tethered to the filler surface This second system represents the limit case of long polymer filler attachment time In this case attention is focused on the free chains of the melt The dynamics in the two models is different In the filled system uniform slowing down for all Rouse modes is observed The effect varies monotonically with the filler polymer affinity Up to saturation this behavior may be captured by usual models with an effective affinity dependent friction coefficient In the system with grafted chains the free chain Rouse dynamics is identical to that in the neat material except for the longest modes which are significantly slowed down More interestingly the dynamics of the free chains depends in a nonmonotonic way on the polymer filler affinity although the free chains do not come in direct contact

    Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=486 (2015-07-15)
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  • RPI SCOREC - Technical Reports
    Scripta Materialia Volume 57 Pages 45 48 Abstract The thermodynamically stable vacancy concentration is evaluated in Al Mg solid solutions by means of atomistic simulations The results are compared with data inferred from experiments based on various models It is shown that in the presence of solute clustering the stable vacancy concentration within the cluster may be orders of magnitude larger than the mean concentration in the absence of clusters

    Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=487 (2015-07-15)
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  • RPI SCOREC - Technical Reports
    macroscale deformation and an overlap interphase sub domain that has a blended description of the two The problem is formulated in terms of equilibrium equations with a blending between the continuum stress and the atomistic force in the interphase Coupling between the continuum and the atomistics is established by imposing constraints between the continuum solution and the atomistic solution over the interphase sub domain in a weak sense Specifically in

    Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=488 (2015-07-15)
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  • RPI SCOREC - Technical Reports
    on a blend of the continuum stress and the atomistic force is adopted for the problem formulation Two error indicators are used for the hierarchy of models consisting of a linear elastic model a nonlinear elastic model and an embedded atom method EAM based atomistic model A nonlinear indicator which is based on the relative error in the energy between the nonlinear model and the linear model is used to

    Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=489 (2015-07-15)
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  • RPI SCOREC - Technical Reports
    that exist in the specimen before deformation During deformation additional solute concentration fluctuation takes place as solute diffuses towards dislocations which themselves form an evolving population Cluster growth takes place at the same rate with cluster dissolution which produces residual clusters i e solute clusters that are not located on a dislocation at given time and are dissolving slowly A conceptual model is used to study the effect of both

    Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=490 (2015-07-15)
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  • RPI SCOREC - Technical Reports
    is one of the primary causes for catastrophic failure in structural materials Here we report an order of magnitude reduction in the fatigue crack propagation rate for an epoxy system with the addition of 0 5 wt of carbon nanotube additives Using fractography analysis and fracture mechanics modeling we show that the crack suppression is caused by crack bridging which results in an effective crack closing stress due to the

    Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=491 (2015-07-15)
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  • RPI SCOREC - Technical Reports
    rate sensitivity and strength are evaluated in terms of the obstacle strength temperature and applied shear stress Above a threshold stress the dislocation motion undergoes a transition from smooth to jerky i e obstacles are overcome in a correlated manner at high stresses while at low stresses they are overcome individually This leads to a significant reduction of the strain rate sensitivity The threshold stress depends on the obstacle strength

    Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=492 (2015-07-15)
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  • RPI SCOREC - Technical Reports
    164907 2006 Its performance in reproducing chain dynamics in a polydisperse melt is tested by extensively comparing the results with those obtained from an equivalent fine scale representation of the same system a bead spring model The coarse grained model is used further to investigate the scaling of the diffusion coefficient with the length of the two types of chains and its dependence on the respective fractions The model reproduces

    Original URL path: http://www.scorec.rpi.edu/reports/view_report.php?id=493 (2015-07-15)
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