Lei Di

Graduation Semester and Year




Document Type


Degree Name

Doctor of Philosophy in Industrial Engineering


Industrial and Manufacturing Systems Engineering

First Advisor

Narges Shayesteh

Second Advisor

Emma Yang


Additive Manufacturing technologies fabricate 3D objects layer by layer following a predesigned CAD model. Owing to the unique layer-wise production method, additive manufacturing offers competitive advantages in comparison with traditional subtractive manufacturing, such as shortened production time, increased design freedom, improved manufacturing capability and complexity, and reduced manufacturing waste. Numerous research studies have been conducted to design, understand, and improve additive manufacturing technologies in order to facilitate the implementation in the supply chain. On the other hand, with the rapid growth of additive manufacturing, sustainability issues that exist on both process level and supply chain level have started to receive increasing public interest. The current literature on additive manufacturing sustainability is mostly focused on process energy consumption, emission, and cost evaluation, towards establishing the life cycle inventory for additive manufacturing and life cycle assessment. Research questions on how to evaluate the recyclability of additive manufacturing waste and how to evaluate the feasibility of additive manufacturing implementation in the supply chain in terms of cost and greenhouse gas emission have not yet been investigated. A comprehensive understanding of material recyclability and additive manufacturing supply chain performance is critical to evaluate the feasibility of large-scale implementation of additive manufacturing towards the circular economy. To fill the knowledge gaps mentioned above, this Ph.D. dissertation aims to establish mathematical models to quantify the cost and greenhouse gas emission of additive manufacturing supply chains and improve performance through supply chain structure innovation and delivery route optimization. Case study results suggest that the overall supply chain cost can be reduced by up to 25.75% and the greenhouse gas emission can be reduced by up to 26.43% when using additive manufacturing in the supply chain. Results also indicate the potential to achieve same-day delivery with less than $20 per order and over 90% delivery rate in 3 hours by properly coordinating the visiting/fabricating sequence. In addition, this Ph.D. dissertation also aims to develop a framework to evaluate the recyclability of additive manufacturing thermoplastic wastes, embedded with quantified tools to investigate the process parameters and their impact on material recyclability in terms of fabrication quality, mechanical properties, and molecular weight distributions. Experimental results indicate that ultimate tensile strength degradation after each round of recycling varies from 27% to 50%, the surface roughness increases by 29.54% after three rounds of recycling, and molecular weight distribution of recycled material demonstrates an obvious shift in each round of recycling. The results generated from this Ph.D. dissertation will help additive manufacturing designers, manufacturers, and users better understand the waste recycling process and design/optimization of additive manufacturing supply chain. The ultimate goal of this research is to facilitate the large-scale implementation of additive manufacturing while achieving circular economy and enabling sustainable additive manufacturing.


Additive manufacturing, Sustainability, Recyclability


Engineering | Operations Research, Systems Engineering and Industrial Engineering


Degree granted by The University of Texas at Arlington