Process parameter influence on high cycle fatigue life of direct metal laser sintered parts

WCU Author/Contributor (non-WCU co-authors, if there are any, appear on document)
Riley W. Seyffert (Creator)
Institution
Western Carolina University (WCU )
Web Site: http://library.wcu.edu/
Advisor
Sudhir Kaul

Abstract: Direct metal laser sintering (DMLS) is a relatively new additive manufacturing (AM) technique. This manufacturing process involves fusing powdered metal layer by layer by using a high-powered laser. Although AM is expected to significantly transform the manufacturing process, there are some limitations that restrict the speed at which parts can be manufactured through the DMLS process. This study focuses on comprehending the influence of process parameters, and parameter interactions, involved in additive manufacturing by using an EOS M290 DMLS machine. A design of experiments is conducted to investigate process parameter in order to determine adequate parameters, or interactions, that can assist in comprehending the DMLS manufacturing process. The parameters tested in this study are layer thickness, laser scan speed, and laser hatch distance. These parameters have been primarily chosen because of their influence on build time. The response variables of the design of experiments include results from dynamic testing through cyclic fatigue. Fatigue testing data is obtained from a custom fatigue testing machine built specifically for this study. Additionally, tensile testing has been conducted to determine ultimate tensile strength.It can be concluded from the results of this study that layer thickness is a significant parameter that needs to be carefully evaluated for fatigue life consideration. The other two parameters tested in this study, scan speed and hatch distance, are seen to be statistically insignificant. Out of all possible parameter interactions tested in this study, the only statistically significant interaction between parameters is that of layer thickness and scan speed. Results from tensile tests conclude that ultimate tensile strength does not seem to be significantly affected by any process parameter. These results highlight the fact that while the static material properties may not be affected by different process parameters, the same conclusion cannot be made about the influence of process parameters on high cycle fatigue characteristics.

Additional Information

Publication
Thesis
Language: English
Date: 2019
Keywords
Additive Manufacturing, DMLS, High Cycle Fatigue

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