Computational Process Model Development for Direct Digital Manufacturing (DDM)

ABSTRACT: Applied Optimization, Inc. (AO) has developed computational process simulation for the prediction of temperature, residual stress, and melt pool control during the material feed DDM processes (e.g. LENSTM and EBFFF). The Phase I work plan is to extend this existing simulation technology for the prediction of temperature, residual stress and melt pool control in commercially available, electron-beam and laser based Ti-6Al-4V powder-bed processes. The Phase I will consist of three tasks. First task is to implement automated procedures to define the simulation model at the beginning of each layer and each time increment of the powder bed process. This will include set up of the material density distribution, material properties, boundary conditions and the finite element model. The second task is to extend the existing methods at AO for thermal and residual stress analysis to powder bed processes. The third task is to demonstrate feasibility of computational modeling of electron beam and laser-based powder bed processes by designing the input power, spot size and deposit geometry for deposit coupons as well as for a representative section of a jet engine component. Depositions will be made and the predictions for temperature, distortions and microstructure will be compared with the experimental data. BENEFIT: Benefits: (1) It will be feasible to perform hands-off automated simulation of laser and electron beam based powder bed processes for complex geometry parts. The simulated entities will include the distribution of temperature, shrinkage, residual stress and distortions. (2) It will become feasible to perform numerical trial and error in order to design process parameters for powder bed processes. Commercial application: This work will complement the existing commercial software at AO for the simulation of additive manufacturing processes. The powder bed simulation technology will become quickly available to the US Industry upon completion of this project due to the existing foundation of commercial work at AO.