## 5 Conclusions  
In this work, a sequentially coupled 3D thermo-mechanical simulation was performed, calibrated and validated for LMD-w process. The effect of interlayer cooling time, clamp constraints, and tool path strategy was investigated to optimize part distortion and residual stress in large-scale laser additive manufactured Ti-6 Al-4V components. The following key findings and conclusions can be made from this study:  
1. The developed numerical simulation shows the capability of predicting the temperature histories and changes in distortion at various process parameter conditions in LMD-w process. The simulated temperature profile and distortion agree well with the measured values.
2. The part distortion decreased with decreasing interlayer cooling times. Also, shorter interlayer cooling time reduced the residual stress. Minimal interlayer cooling time is recommended to mitigate the plate distortion and residual stress as well as increase build productivity.
3. Full clamp constraint was more effective at reducing part distortion compared to the center clamp. However, in the full clamp condition, high stress concentrations caused corner cracking at the corner of the interface between the wall and plate.
4. A unidirectional tool path led to spatially non-uniform stress distribution over the part, while a bidirectional tool path with 180\({}^{\circ}\) rotation improved the symmetricity of stress distribution.
5. Compared to DB-5, a bidirectional tool path with 180\({}^{\circ}\) rotation in DB-1 decreased the residual stress by approximately 50% at the bottom corner, which potentially reduces the susceptibility to cracking.  
Ongoing work includes an extension of the simple two-bead wall geometry to practical industrial geometries. Then, the model can be used to control microstructure, distortion and residual stress to achieve a high-quality part at a given complex geometry in the LMD-w process.  
Conceptualization, Y.L. and Y.B.; methodology, Y.L. and S.S.; validation, Y.B. and B.T.G.; resources, B.R. and S.S.; data curation, Y.L.; writing-original draft preparation, Y.L., P.N. and B.T.G.; writing-review and editing, P.N. and S.S.; supervision, S.S. and B.R., project administration, B.R. and S.S.; funding acquisition, B.R. and S.S.  
**Funding:** The research was funded by the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office under contract DE-AC05-00 OR22725 with UT-Battelle, LLC. This work is also supported in part by Cooperative Research and Development Agreement with GKN Aerospace, under contract No. NFE-15-05725. The United States government retains and the publisher, by accepting the article for publication, acknowledges that the United States government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE public access plan ([[http://energy.gov/downloads/doe-public-access-plan](http://energy.gov/downloads/doe-public-access-plan)]([http://energy.gov/downloads/doe-public-access-plan](http://energy.gov/downloads/doe-public-access-plan))).  
**Acknowledgments:** The authors like to acknowledge the contribution of the extended Oak Ridge National Laboratory and GKN Aerospace teams, particularly those of [PERSON] of ORNL and [PERSON], [PERSON] and [PERSON] of GKN Aerospace.  
**Conflicts of Interest:** The authors declare no conflict of interest.