Comparative life cycle energy assessment of lightweight multi-material metal-fiber composite hybrid body-in-white designs

Lightweighting is crucial for enhancing vehicle efficiency and reducing tailpipe emissions. Fiber-reinforced plastic (FRP) composites for the Body-in-White (BIW) are a major research focus aimed at achieving lightweighting. FRP composite manufacturing processes, such as vacuum infusion or automated fiber placement, cannot meet the automotive industry's rates, cycle times and large production volumes. From a cost standpoint, as component size and scale of manufacturing increase, material cost becomes the dominant factor in production, inhibiting the use of expensive composite materials. Thus, multi-material structural designs have taken center stage, where lightweight materials and high-rate composite manufacturing processes are strategically used in conjunction with traditional metallic designs.

A highly integrated multi-material, FRP-intensive BIW design was developed using unique multi-material metal-fiber transition joints that enable spot welding of composite parts. This allows a multi-material BIW to be manufactured with minimal change to the vehicle manufacturer's assembly and joining infrastructure, presenting a cost-effective solution to integrate composites. From a sustainability standpoint, the life cycle impact of these multi-material designs and composite manufacturing methodologies must be investigated and compared with contemporary sheet-metal designs. A comprehensive comparative life cycle energy assessment has been performed on the proposed multi-material designs manufactured using fast-cycle composite manufacturing processes. Determining the cumulative energy demand over the entire life cycle of the multi-material BIW provides valuable insights into the material composition of the multi-material BIW. It also helps establish a trade-off between the use of energy-intensive composite materials and the energy savings achieved during the use stage due to lightweighting.