MODELING AND PREDICTING STRESSES IN THERMOSET MATERIALS Sandia National Laboratories has developed a system for fully three-dimensional finite element modeling for analyzing curing process in low molecular weight resins and condensation type reactions (i.e. epoxies used in encapsulation). Cure modeling validated to within 10% of actual performance. Utilize thermal chemical code to predict reaction rate, exotherms and heat transfer associated with cross-linking reaction. Results are passed on to a structural code which computes the cure-shrinkage and accompanying evolution in viscoelastic properties needed to predict the deformations and stresses generated during cure. Urethanes and polyesters would also be relevant in applying the model. An advancement of the cure modeling capability is the use of non-linear viscoelasticity to predict dimensional stability, physical aging, and stresses through yield in polymers. This modeling capability is complimentary to the cure modeling and can be used for analyzing the non-linear thermoviscoelastic deformations and stresses in polymers subjected to arbitrary loading histories. Both modeling approaches utilize massively parallel computing Teraflops computer and proprietary three-dimensional finite element analysis codes. Facilities to characterize time-temperature-reaction dependent viscoelastic properties of polymers and prediction of yielding in shear, compression, and tension as well as combined loadings. Important applications include: Electronic packaging. Composite materials. Adhesively bonded joints. Encapsulation of PCBs and electrical components. Dimensional stability of polymers. Automotive paints. Physical and chemical aging and dimensional stability of polymers. Developing failure models. Potential Benefits Sandia codes are more specific in their iterative approach and therefore more effective and productive than commercially available modeling software. Diagnosis of performance characteristics with recommended changes in process to improve performance. Cure schedules shortened. Stresses, warpage and deformations optimized using analysis to tailor process parameters (temp., time) a priori. Reduce the number of proof tests needed and shorten time to market while improving quality and reliability. True process modeling of parameters affecting end product. Accurate prediction of stresses in failure models and prediction of dispersive waves in shock propagation problems. Demonstrated Achievements Reduced development time on defense components by 50% Follow-up This proprietary Sandia capability may be applied to solve challenging problems in the field of polymer and other organic sciences. Sandia has the flexibility to form specific teams of technical experts from any or all of the above capabilities to focus expertise on specific technical challenges. We are interested in making this technology available to companies responsive to partnering with Sandia to develop near/term and/or future applications via licensing or cooperative development agreements. For further information, please respond by mail or fax to Joanne Trujillo no later than December 8, 1998 at: Sandia National Laboratories, MS 1380, P. O. Box 5800, Albuquerque, New Mexico 87185-1380. Fax: (505) 843-4163. Please indicate the date and title of this CBD notice. E-MAIL: Joanne Trujillo, jmtruji@sandia.gov. Posted 11/24/98 (W-SN274628).

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