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Wetting and free surface flow modeling for potting and encapsulation

Adolf, Douglas B.; Castaneda, Jaime N.; Kraynik, Andrew M.; Noble, David R.; Sun, Amy C.; Cote, Raymond O.; Grillet, Anne M.; Notz, Patrick N.; Brooks, Carlton F.; Givler, R.C.; Hopkins, Matthew M.; Mondy, L.A.; Rao, Rekha R.

As part of an effort to reduce costs and improve quality control in encapsulation and potting processes the Technology Initiative Project ''Defect Free Manufacturing and Assembly'' has completed a computational modeling study of flows representative of those seen in these processes. Flow solutions are obtained using a coupled, finite-element-based, numerical method based on the GOMA/ARIA suite of Sandia flow solvers. The evolution of the free surface is solved with an advanced level set algorithm. This approach incorporates novel methods for representing surface tension and wetting forces that affect the evolution of the free surface. In addition, two commercially available codes, ProCAST and MOLDFLOW, are also used on geometries representing encapsulation processes at the Kansas City Plant. Visual observations of the flow in several geometries are recorded in the laboratory and compared to the models. Wetting properties for the materials in these experiments are measured using a unique flowthrough goniometer.

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TYPE SAND Report YEAR 2007
OSTIDOI

Adhesive joint and composites modeling in SIERRA

Hammerand, Daniel C.; Chambers, Robert S.; Brown, Arthur B.; Foulk, James W.; Adolf, Douglas B.; Ohashi, Yuki O.

Polymers and fiber-reinforced polymer matrix composites play an important role in many Defense Program applications. Recently an advanced nonlinear viscoelastic model for polymers has been developed and incorporated into ADAGIO, Sandia's SIERRA-based quasi-static analysis code. Standard linear elastic shell and continuum models for fiber-reinforced polymer-matrix composites have also been added to ADAGIO. This report details the use of these models for advanced adhesive joint and composites simulations carried out as part of an Advanced Simulation and Computing Advanced Deployment (ASC AD) project. More specifically, the thermo-mechanical response of an adhesive joint when loaded during repeated thermal cycling is simulated, the response of some composite rings under internal pressurization is calculated, and the performance of a composite container subjected to internal pressurization, thermal loading, and distributed mechanical loading is determined. Finally, general comparisons between the continuum and shell element approaches for modeling composites using ADAGIO are given.

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TYPE SAND Report YEAR 2005
OSTIDOI

The relationship between polymer mobility and potential energy

Adolf, Douglas B.; Budzien, Joanne L.

The WLF equation is typically used to describe the dependence of polymer mobility on temperature at atmospheric pressure. Tests at different pressures would at least require different WLF parameterization. Completely different tests, for example, probing the temperature dependence of mobility at constant density, would require even greater modifications. By performing molecular dynamics simulations on simple chain molecules equilibrated at different thermodynamic states, we have shown that the mobility depends in a more general sense on the potential energy density of the system. That is, mobilities for any equilibrated state collapse onto one master curve when plotted against the potential energy density. Moreover, this relationship can be fit by either a 'generalized' WLF equation or by a power-law relationship observed in critical phenomena. When this mobility relationship is used within a rheologically simple, thermodynamically consistent, viscoelastic framework, quantitative agreement is seen between experimental data and theoretical predictions on a range of tests covering enthalpy relaxation to mechanical yield to physical aging.

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TYPE Conference YEAR 2005
OSTI

General relationships between the mobility of a chain fluid and various computed scalar metrics

Proposed for publication in the Journal of Chemical Physics.

Adolf, Douglas B.

We performed molecular dynamics simulations of chain systems to investigate general relationships between the system mobility and computed scalar quantities. Three quantities were found that had a simple one-to-one relationship with mobility: packing fraction, potential energy density, and the value of the static structure factor at the first peak. The chain center-of-mass mobility as a function of these three quantities could be described equally well by either a Vogel-Fulcher type or a power law equation.

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TYPE Journal Article YEAR 2004
OSTI
Results 26–50 of 55
Results 26–50 of 55