Browsing by Subject "Shape Deposition Manufacturing"

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    Control of Residual Thermal Stresses in Shape Deposition Manufacturing
    (1995) Chin, R.K.; Beuth, J.L; Amon, C.H.
    Layer-level thermal and mechanical modeling ofthe microcasting stage of ShaPe Deposition Manufacturing is presented. Thermo-mechanical models of carbon steel deposited onto a carbon steel substrate are described. Mechanics modeling addresses the issue of residual stress build-up. The effects of substrate heating and bending constraint on the build-up of residual stresses are shown. Results show that thermal cycling from newly applied droplets drastically changes the stress state in the top of the substrate. Originally unstressed regions go through an inelastic compression-tension stress cycle. Residual stresses reach values that may cause yielding in carbon steel. Moderate heating of the substrate above room temperature prior to droplet deposition reduces stresses significantly. Bending constraint during part manufacture allows partial relaxation of stresses as the constraint is removed.
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    Layered Manufacturing Material Issues for SDM of Polymers and Ceramics
    (1997) Kietzman, J. W.; Cooper, A. G.; Weiss, L. E.; Schultz, L.; Lombardi, J. L.; Prinz, F. B.
    Shape Deposition Manufacturing (SDM) is a solid freeform fabrication process which enables the manufacture of structural parts from engineering materials. This paper discusses the requirements and constraints for SDM part and sacrificial support materials, including chemical and physical compatibility, mutual adhesion, low shrinkage, machinability, and support material removability. Polymers and ceramics processed by SDM include polyurethanes, epoxies, polyurethane foams, photocurable acrylics, and green alumina ceramics. SDM compatible support materials include waxes, water-soluble polyacrylate soldermasks, and water-soluble thermoplastics. This paper details the selection of SDM part and support material combinations for the fabrication of polymer prototypes and polymer molds for ceramic prototyPes.