Concept study for battery crash profiles using 5xxx and 6xxx aluminium sheet
The additional weight of the battery, the dimensions of the battery pack as well as the high safety requirements of the battery cells inside battery electric vehicles (BEVs) are leading to high demands regarding the crash performance.
Especially the side pole crash test is very critical. To pass this test, most of the modern batteries are protected by separate crash profiles. At the moment there are basically two approaches. One is using extruded aluminium profiles, the other is using rollformed steel profiles.
Extruded aluminium profiles are frequently used solutions when it comes to crash management and battery protection.
One of the major advantages of this approach is the light weight achieved by combining Aluminium with a complex profile cross section. Furthermore, the profile benefits of high corrosion resistance of Aluminium, which allows to omit an additional corrosion protection in some circumstances.
Drawbacks are the limited flexibility if the profile cross section needs to be changed. New profile designs require new tools. Furthermore, additional manufacturing steps like cutting, milling, or drilling that cannot be incorporated into (existing) production lines.
Due to its high strength, steel seems to be a suitable option to design crash profiles. However, the higher density of steel leads to a higher weight of the final products and additional corrosion protection is mandatory due to the poor corrosion resistance of steel.
Yet, the today used solutions, based on rollformed steel, have some valuable advantages in comparison to extruded crash profiles. Because of the rollforming process, different types of profiles can be created with only minor tool adjustments. Additionally, incorporation of milling, cutting, and drilling operations into the rollforming line is state of the art. These advantages lead to high overall productivity, which is especially beneficial when it comes to higher production volumes.
Can we use the best of both approaches?
With the right concept, we can!
Using the advantages of both approaches is possible but requires a smart profile design and the appropriate material choice. Therefore, it is crucial to reduce the complexity of the profile, especially in regard to the welding operations.
Otherwise, the solution would not meet light weight requirements and the costs would not be competitive. Because of cost and productivity reasons, any offline manufacturing steps must be avoided if possible. For the technical performance the material thickness of each part and especially the position and geometry of the beads is crucial.
In the present study, we developed a profile-in-profile concept (Figure 1), that meets all of the above outlined targets. Combined with a high strength 5xxx or 6xxx aluminium solution, competitive profiles can be produced for BEV applications. Drop tower simulations indicate a similar performance as extruded aluminium profiles (Figure 2), which are the current benchmark.
Figure 1: Schematic illustraton
Figure 2: Simulation of drop tower test
Benefits of rollformed aluminium
To summarize, we see a great potential for rollfomed aluminium profiles for battery protection by combining the advantages of extruded aluminium profiles and rollformed steel profiles. Also, this approach adds the possibility to design a battery housing using only one alloy, 5xxx or 6xxx series.
- Same tools can be used to manufacture different profiles
- In-line manufacturing steps (cutting, stamping, …)
- No additional corrosion protection needed
- Potential cost reduction
- Shorter production time
- Enable uni-alloy concept 5xxx or 6xxx
- Light-weight design
Concept study for battery crash profiles
Aluminiumstraße 1 41515 Grevenbroich Germany