ENERGY CONSUMPTION AND CARBON EMISSIONS OF ADDITIVE MANUFACTURING USING SMART MATERIALS: A SUPPLY CHAIN PERSPECTIVE

The use of stimuli-responsive materials in additive manufacturing offers new opportunities for fabricating smart structures with time-evolving properties, which is termed as 4D printing. 4D-printed structures can change their shapes over time when triggered by external stimuli, such as heat, moisture, and light, which leads to promising applications in robotics, prosthetic devices, self-folding products, etc. In the current literature, material discovery and characterization have been extensively reported for 4D printing processes, along with advanced modeling and simulation from the structure-to-functionality perspectives. However, the potential impacts of 4D printing technology on supply chain sustainability, particularly concerning energy use and carbon emissions, remain largely unexplored. In this study, mathematical models are established to quantitively analyze how the adoption of 4D printing technology affects energy consumption and carbon emissions during different stages of supply chains. An exploratory comparison is performed using a protective enclosure for microcontroller board under two scenarios, i.e., the components fabricated using stereolithography with conventional resin needing manual assembly upon use, and a 4D-printed monolithic case with heat-activated self-folding on demand. Case study results indicate that the use of 4D printing contributes to more energy-efficient operations in the supply chain with an approximately 10% reduction in carbon emissions.