Lightweight Material Technology for Electric Vehicles: Balancing Weight Reduction and Performance from Aluminum Alloy to Carbon Fiber

Keywords: electric vehicle lightweight, aluminum alloy, carbon fiber, high-strength steel, composite materials

abstract

Lightweight is the key path to improving the range of electric vehicles. This article analyzes the technical challenges and commercial solutions from material selection, connection process to cost optimization.

5.1 Limitations of Traditional Materials

High strength steel (HSS): with a density of 7.8g/cm 3, it has limited potential for weight reduction (such as the Tesla Model 3 still using 50% steel for its body).

Aluminum alloy: density 2.7g/cm 3, but poor weldability (such as a 30% decrease in welding strength of 6000 series aluminum alloy), requiring riveting or bonding processes.

5.2 Advanced Aluminum Alloys and Forming Processes

7 Series Aluminum Alloy (Al Zn Mg Cu): With a tensile strength of 580MPa and a specific strength twice that of steel, it is used for the NIO ET7 body frame, reducing weight by 15%.

Semi solid casting: The motor housing is produced through rheological casting technology, with a porosity of less than 1% and a thermal conductivity increase of 20% (180W/m · K).

5.3 Application of Carbon Fiber Composite Materials

Thermoplastic carbon fiber: using Teijin Tenax TPC prepreg, the molding cycle is shortened from 2 hours to 5 minutes, and the cost is reduced by 40% (from 20/kg to 12/kg).

Localized enhancement technology: Carbon fiber reinforced plastic (CFRP) is embedded in the A-pillar of the BMW i3 body, increasing collision energy absorption efficiency by 30%.

5.4 Multi material Connection and Simulation

Self piercing riveting (SPR): Connect aluminum alloy and high-strength steel through Henrob SPR equipment, with a joint strength of 15kN and a fatigue life of 10 ⁵ times.

Topology optimization design: Using Altair OptiStruct software, the weight of the battery tray is reduced by 25% while ensuring stiffness (torsional stiffness>25000N · m/°).

5.5 Cost and Recycling Challenges

Carbon fiber recycling: Carbon Conversions in Germany uses pyrolysis to recycle carbon fiber, with a recovery rate of over 90% and a cost of 8/kg (20/kg for primary fibers).

LCA full lifecycle assessment: The carbon emissions of aluminum alloy car bodies are 20% lower than those of steel car bodies (for example, the lifecycle carbon emissions of Jike 001 aluminum alloy car doors are 12kg CO ₂ e/kg).

conclusion

Lightweight design requires a balance between performance and cost. Through multi material collaborative design, advanced molding processes, and recycling technologies, the dual goals of electric vehicle range and environmental protection can be achieved.