For a long time, the application of carbon fiber composite materials in the automotive industry has been debated around a focus: Is it worth paying the extra high cost for carbon fiber composite materials?
A comparison of a recent project by Bold Valuely Tech on this issue concluded that carbon fiber composites are really worth it!
In this project, the target product is the inverter housing assembly, which is a unit that contains the battery and allows it to communicate with other components (mainly the motor).
The traditional material used for this component is aluminum alloy, and Bold Valuely Tech came to a surprising conclusion by comparing aluminum and carbon fiber composites:
The carbon fiber composite structure is 91% lighter than the aluminum alloy. For one chassis, the aluminum alloy component weighs 6746 grams, while the carbon fiber component weighs only 616 grams, which is equivalent to 1/11 of the weight of the aluminum part.
Aluminum has long been the material of choice for this part of construction. After all, carbon fiber composites have received little attention because they are so well known and natural for people to use the material.
In fact, carbon fiber composites are just as effective as aluminum, with the distinct advantage that machined structural parts can be lighter. The team that brought all the components together at the beginning of the project did want to keep costs down, which is probably why carbon fiber composites were overlooked in the design stages of power electronics and batteries.
Because of the high price quoted for carbon fiber composites, there is a willingness to accept the material; while Bold was confident that the budget would not be exceeded when conducting the comparative tests, they wanted to reiterate the fact that the performance of the material will eventually outweigh the cost factor. This can even translate into cost savings over the life of the vehicle.
Compared to aluminum alloys, titanium alloys, and steel, etc., which have a stiffness ratio of about 25 GPa/(g/cm3), carbon fiber composites range from 66 to 150 GPa/(g/cm3), which makes it an advantage of 3 to 6 times. The actual focus should be on mitigating important advantages, and for specific applications, such as in high-level motorsport, weight reduction does pay off in the long run.
Advantages of carbon fiber composites
In Bold's Inverter Housing Project study, the weight of the current use of aluminum components was compared with the possible replacement of carbon fiber.
In this study, the structure was not carefully examined because the structure made of aluminum was not optimized, but it is important to emphasize that any other In the study, these results were similar, and the results proved that the weight of the carbon fiber composite structure was 91% lighter than that of the aluminum alloy, and the aluminum alloy chassis alone weighed 6746 grams, while the carbon fiber chassis weighed only 616 grams, which is equivalent to aluminum. 1/11 of the weight of the manufactured part.
The above comparison is only the most obvious improvement when replacing the material with carbon fiber, but it is not the only improvement. Choosing carbon fiber also brought some other notable improvements that paid off over time. Compared to metal, carbon fiber offers the following advantages and even cost savings:
By adding layers of different materials, it is easy to electrically insulate internal or external surfaces. This is important for high voltage applications where safety can be an issue in the event of a crash or catastrophic unit failure
Easily implement complete Faraday cages that meet EMC requirements
Metal-like electrical connections between inserts
Carbon fiber composites can resist corrosion
Sensors can be embedded in carbon fiber composite structures
Carbon fiber composites come in different shapes and forms, with Bold being the most common carbon fiber prepreg used in the tests. These layers of material have resin and a reinforcement layer (usually epoxy with carbon fiber fabric). In prepreg, the two components, resin and reinforcing carbon fiber, are first "pre-mixed" and ready to be laid in the mold; after the materials are laminated in the mold, heat and pressure are applied to cure the resin to prepare the structural part.
Overall, carbon fiber offers significant advantages for automotive applications. However, due to cost constraints in the mainstream market, carbon fiber composites mainly exist in sports car to supercar categories as well as in motorsport.
About Bold
Established in 2019 and led by former Formula 1 engineers, Bold's expertise lies in the light-weighting of structural components with the use of advanced composite materials and the development of bespoke high-voltage energy storage solutions. The company consists of a team of over 35 engineers that serve a global client base in sectors such as Formula 1, Automotive, Aerospace and Renewables.