Computational Process Model Development for Direct Digital Manufacturing (DDM)

ABSTRACT: Powder-bed based additive manufacturing (AM) technologies typically involve rapid solidification after a laser or electron beam melts a region of powder. Although parameters can be optimized for lowest cost, highest precision, or optimum microstructure, these optimizations require trade-offs between scan rate, layer thickness, bed heating, and use of support materials. Input from Continuous Cooling Transformation (CCT) diagrams, thermo-mechanical boundary conditions, 3-Dimensional Finite Volume (3DFV) methodology, and part geometry in the form of an STL file, will be utilized in University of Louisville"s (U of L) Dislocation Density based Crystal Plasticity Finite Element Model (DDCP-FEM) to predict local and global strengths, grain morphologies, and other layer-by-layer interfacial characteristics. By coupling this model with a direct metal laser sintering (DMLS) development cell, constructed at Mound Laser & Photonics Center (MLPC), parameters determined by the software will be experimentally tested, validated, and used for input in the iterative model. Upon validation between model and development cell, a high aspect ratio feature of a OEM selected component will be fabricated using a commercial DMLS station at both the U of L and General Electric Aviation (GEA). BENEFIT: Due to the lengthy development time and cost found in current direct digital manufacturing (DDM) technologies, the proposed work would provide savings in cost and time for fabricating complex components from a digital design. Commercial propulsion and airframe applications stand to greatly benefit from improved DDM especially by the elimination of tooling, dies, and casting molds. The time savings for engineering development in the form of rapid prototyping of designs as well as complex geometries that do not lend themselves to conventional machining techniques would greatly benefit both commercial and military applications.