The Woodruff School

SUMMARY

Cellular materials have been used for engineering applications during the past three decades due to their favorable mechanical characteristics. However, conventional subtractive manufacturing processes are not suitable for cellular materials because of their complex geometries. Recently, additive manufacturing (AM) processes have begun to offer new opportunities to produce cellular materials. AM�s layer stacking process allows users to fabricate complex geometries with no additional effort. Although the AM technique can be a good solution for overcoming manufacturing difficulties, the mechanical properties of a fabricated cellular material cannot be guaranteed due to the inherent limitations of the AM process. In this context, the purpose of this research is to develop a method to predict the mechanical properties of a cellular material by considering the effects of the AM processes.
Many phenomena are involved in the fabrication of a cellular material using the AM process. In order to more clearly understand the AM process, related parameters are categorized into four groups based on manufacturing stages: (a) design and manufacturing process parameters, (b) layer deposition parameters, (c) structural element parameters, and (d) lattice structure properties. Three transformations are defined among these groups. The goal of this research is to define those transformations. To address this goal, three research questions will be investigated by this research:
� How is the functional relationship between the design and manufacturing process parameters and the layer deposition parameters quantitatively explained?
� How is the propagation of geometrical and material variations from the layer deposition parameters to structural element parameters quantitatively described through the repeated stacking procedure?
� What numerical procedure could be implemented in order to formulate an estimation procedure for the mechanical properties of a periodic cellular material fabricated by the AM process?
The intellectual merit of this research lies in developing a numerical procedure to estimate the mechanical properties of cellular material, which include AM process effects. The scientific and engineering outcomes from this research will help cellular materials to be implemented for conventional applications and will aid in the design and manufacture of advanced cellular materials.

SUBJECT:	Ph.D. Proposal Presentation

BY:	Sang-In Park

TIME:	Friday, January 23, 2015, 10:00 a.m.

PLACE:	MRDC Building, 4211

TITLE:	Estimating Mechanical Properties of Cellular Solid Materials from Additive Manufacturing Processes

COMMITTEE:	Dr. David Rosen, Chair (ME) Dr. Seung-kyum Choi (ME) Dr. Yan Wang (ME) Dr. Massimo Ruzzene (AE) Dr. Chad Duty (ORNL)

SUMMARY Cellular materials have been used for engineering applications during the past three decades due to their favorable mechanical characteristics. However, conventional subtractive manufacturing processes are not suitable for cellular materials because of their complex geometries. Recently, additive manufacturing (AM) processes have begun to offer new opportunities to produce cellular materials. AM�s layer stacking process allows users to fabricate complex geometries with no additional effort. Although the AM technique can be a good solution for overcoming manufacturing difficulties, the mechanical properties of a fabricated cellular material cannot be guaranteed due to the inherent limitations of the AM process. In this context, the purpose of this research is to develop a method to predict the mechanical properties of a cellular material by considering the effects of the AM processes. Many phenomena are involved in the fabrication of a cellular material using the AM process. In order to more clearly understand the AM process, related parameters are categorized into four groups based on manufacturing stages: (a) design and manufacturing process parameters, (b) layer deposition parameters, (c) structural element parameters, and (d) lattice structure properties. Three transformations are defined among these groups. The goal of this research is to define those transformations. To address this goal, three research questions will be investigated by this research: � How is the functional relationship between the design and manufacturing process parameters and the layer deposition parameters quantitatively explained? � How is the propagation of geometrical and material variations from the layer deposition parameters to structural element parameters quantitatively described through the repeated stacking procedure? � What numerical procedure could be implemented in order to formulate an estimation procedure for the mechanical properties of a periodic cellular material fabricated by the AM process? The intellectual merit of this research lies in developing a numerical procedure to estimate the mechanical properties of cellular material, which include AM process effects. The scientific and engineering outcomes from this research will help cellular materials to be implemented for conventional applications and will aid in the design and manufacture of advanced cellular materials.