Advanced lightweight materials and manufacturing processes for automotive applications - Volume 40 Issue 12 - Alan I. Taub, Alan A. Luo

Microwave absorbing materials, particularly ones that can achieve high electromagnetic interference (EMI) absorption while minimizing weight and thickness are in high demand for many applications. Herein we present an approach that relies on the introduction of periodically placed air-filled pores into polymer composites in order to reduce material requirements and maximize microwave absorption. In this study, graphene nano platelet (xGNP)/poly-lactic acid (PLA) composites with different aspect ratio fillers were characterized and their complex electromagnetic properties were extracted. Using these materials, we fabricated non-perfect electrical conductor (PEC) backed, porous composites and explored the effect of filler aspect ratio and pore geometry on EMI shielding properties. Furthermore, we developed and experimentally verified a computational model that allows for rigorous, high-throughput optimization of absorbers with periodic porous geometries. Finally, we extend the modeling approach to explore the effect of pore addition on PEC-backed composites. Our composite structures demonstrated decreased fractions of reflected power and increased fractions of absorbed power over the majority of the X Band due to the addition of periodically arranged cylindrical pores. Furthermore, we showed that for xGNP/PLA composite material, reflection loss can be increased by as much as 13 dB through the addition of spherical pores. The ability to adjust shielding properties through the fabrication of polymer composites with periodically arranged pores opens new strategies for the modeling and development of new microwave absorption materials.

We assess the cradle-to-grave greenhouse gas (GHG) emissions of current (2025) light-duty vehicles (LDV) across powertrains, vehicle classes, and locations. We create driver archetypes (commuters, occasional long-distance travelers, contractors), simulate different use patterns (drive cycles, utility factors, cargo loads) and characterize GHG emissions using an attributional approach. Driven by grid decarbonization and improved electric vehicle efficiency, we are first to report electric vehicles have lower GHG emissions than gasoline vehicles in every county across the contiguous United States. On average, a 300-mile range battery electric vehicle (BEV) has emissions which are 31-36% lower than a 50-mile range plug-in hybrid electric vehicle (PHEV), 63-65% lower than a hybrid electric vehicle (HEV), and 71-73% lower than an internal combustion engine vehicle (ICEV). Downsizing also reduces emissions, with a compact ICEV having 34% lower emissions than an ICEV pickup. We present the first evaluation of LDV emissions while hauling cargo, showing that carrying 2500 lbs. in a pickup increases BEV emissions by 13% (134 to 152 g CO₂e/mile) compared to 22% (486 to 592 g CO₂e/mile) for an ICEV. Emissions maps and vehicle powertrain/class matrices highlight the interplay between vehicle classes, powertrains, locations, and use patterns, and provide insights for consumers, manufacturers, and policymakers.