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Composites in automotive applications are becoming more of the norm to help with decreasing weight and increasing strength. In the context of automotive applications, a composite is a material made from two or more constituent materials with significantly different physical or chemical properties. When combined, these materials produce a composite with characteristics different from the individual components. From engine components to suspension arms and links to body panels, composites have been present in the automotive industry for a very long time. 

As with any component, age and ultraviolet (UV) radiation will break down the materials over a period of time. Couple UV exposure with the multiple thermal cycles these materials are exposed to within a short period of time, and the abilities of composite materials are constantly being tested. Some of these materials react better than others, which will lead us into a discussion on the types of composites currently being used and how those materials are utilized in automotive manufacturing.  

Types of Composites Used in Automotive Vehicle Construction
The automotive industry increasingly relies on advanced composites to enhance vehicle performance, safety, and efficiency. These types of materials provide the OEMs with the ability to meet the requirements of government regulations and customer desires for efficient vehicle operation. Maximizing the output of the vehicle to help with minimizing the operational costs associated with owning a vehicle will further increase their use case. Reducing the weight of the curb vehicle by a mere 10% can reduce energy consumption by six to eight percent. This change is vital as the transition to electric vehicles (EV) continues. The efficient use of energy contained in the battery pack is crucial to conditioning the consumer to adopt an EV into their transportation strategy. Another feature of utilizing composite materials is the ability to source components that do not require heavily refined minerals which helps manufacturers control costs and increase output potential of the facilities where they are created. 

Carbon Fiber Composites
Carbon fiber composites are renowned for their exceptional strength-to-weight ratio. These materials consist of carbon fibers embedded in a polymer matrix, providing unrivaled stiffness and durability. Carbon fiber is one of the first types of materials utilized in automotive applications because of their strength and weight reduction as opposed to steel. With a high strength to weight ratio, the ability of carbon fiber to replace the usage of aluminum or steel components has made it vital to the automotive supply chain. Carbon fiber components have been around since the 1950’s in automotive and aviation applications. 

The ability to shape components into any desired shape, while maintaining the integrity of the structure, increases manufacturing abilities and applications. Until recently the carbon fiber has been cost prohibitive for most applications, but with the increasing cost of vehicles and increased demand for fuel efficiency from the government regulator, the increased use has brought the price down to a point it is viable for production automobiles. Most carbon fiber composites are created out of polyacrylonitrile (PAN), which is synthetic thermoplastic and is polymerized through a heavily energy intensive process. These types of materials do not easily dissolve in chemicals and must be created in such a way they are woven into a fiber type of material that can be formed into almost any shape.  

Glass Fiber Reinforced Polymer Composites
Glass fiber reinforced polymer composites (GFRP), also known as fiberglass, are widely used in the automotive industry due to their affordability and versatility. Comprising glass fibers embedded in a polymer matrix, these composites offer excellent strength and impact resistance. These are one the most popular types of composites because of their ease of manufacture. The ability of fiberglass material to be formed in a variety of shapes and sizes makes it an ideal component for use in the automotive industry. The strength of these types of composites are comparable to steel, with greater stiffness than aluminum and less density than steel. Body panels have highly defined shapes along with the ability to resist deformation when struck by an object. This resilience helps to make a very robust body panel. Utilizing GFRP composites makes components highly cost effective, easily moldable and reasonably similar in strength to much heavier materials.  

Natural Fiber-Reinforced Polymer Composites
Natural fiber-reinforced polymer (NFRP) composites are an emerging class of materials that incorporate fibers derived from renewable sources, such as flax, hemp, and jute. These composites offer an environmentally friendly alternative to traditional synthetic fibers, with the added benefits of reduced weight and improved sustainability. Natural fiber composites are used in non-structural automotive components, such as interior panels, trim, and insulation. Natural fiber composites are increasingly being utilized in the automotive industry due to their environmental benefits, cost-effectiveness, and desirable mechanical properties. These composites are made by reinforcing a polymer matrix with natural fibers such as flax, hemp, jute, and sisal.  

The automotive sector's shift towards sustainability and lightweight materials has driven the adoption of natural fiber composites. The increasing use of these bio-composite components will help to make more of the automotive industry shift to a lower greenhouse warming potential (GWP) material which will help to lower the impact of its production on the environment. Utilizing these types of natural fibers within interiors of vehicles will reduce the exposure of the driver and passengers to potential caustic materials that are currently being used for trim, upholstery and other interior components. Mimicking the strength of conventional composites provides a similar use case with a more sustainable material.  

Along with a better product for the environment, the use of natural fiber composites is usually more cost effective than the alternative. Being able to recycle more of the vehicle than before, OEMs can then utilize the recycled content to produce new vehicles in a never-ending supply chain. Combining this recycled content with virgin material will also lower the cost of production of those components, thus making the OEMs more money per unit. One of the downsides of NFRP composites is the ability of the natural fibers to absorb water. Over time these materials will degrade as moisture intrudes on their substructure which has caused the OEMs to focus on how to utilize surface treatments and other materials to seal the fibers so moisture intrusion can be kept to a minimum. Another thing that limits their use is since these materials are naturally found the variability of the materials is vast which can cause usage issues as not all fibers are exactly the same. The mixture of the polymer must be adjusted based on the crop of materials that are presently in the mixture.  

Hybrid Composites
Hybrid composites are usually defined as a composite that consists of an organic polymer and one or more inorganic additives/fillers. Combining the different properties of the organic and the inorganic materials will provide one of the most usable types of composites for automotive applications. Hybrid composite materials are used in various automotive components, including structural parts, body panels, and reinforcements. With “hard parts” (materials that are minimal or non-force absorbing) comprising most of its uses, hybrid composites are also being utilized in crash management applications “soft parts” (force absorbing) that can absorb some of the impact should a collision occur. Directing the force through the material to another component can help to protect the occupants in the vehicle while at the same time providing for cost savings utilizing nature materials to help augment the higher costs produced materials.  

Polymer Matrix Composites (PMCs)
Polymer matrix composites (PMCs) are the most commonly used composites in automotive construction. These materials consist of a polymer matrix reinforced with fibers, such as carbon, glass, or natural fibers. PMCs offer a wide range of mechanical properties and can be tailored to meet specific performance requirements. The use of PMCs include body panels, engine components, and interior parts. Polymer matrix composites (PMCs) are increasingly used in the automotive industry due to their lightweight, high strength, and versatility. These composites consist of a polymer matrix, such as epoxy, polyester, or polypropylene, reinforced with fibers like glass and carbon. As these components do not have any ferrous materials in them, they are resistant to corrosion and other potential oxidation. Utilized in everything from intake manifolds, valve covers and body panels the thermal stability of the material provides for a robust component that will last for a long period of time.  

Metal Matrix Composites (MMCs)
Metal matrix composites (MMCs) are composed of a metal matrix, such as aluminum or magnesium, reinforced with ceramic or metallic fibers. MMCs provide superior strength, stiffness, and thermal resistance compared to traditional metals. These types of materials are currently being utilized in powdered metal types of applications such as camshafts and other internal engine components. The mixture of the material provides for a very dense, hard material that has a higher thermal stability than a machines component. MMCs can also be utilized in other high wear, high temperature applications such as brake rotors to minimize the wear of the actual rotor over time. Increasing the life span of these components decreases the cost over time to the owner as repairs become less frequent. These types of materials are created by combining two or more metal-based alloys and usually a reinforcement which is most of the time including ceramics which provides thermal enhancement. The types of materials are usually customized per application and highly complex to create based on the types of elements included in the mixture. Their increased hardness and thermal capabilities make them tough to work with after they have been formed. This is usually the reason they are custom formed to the particular shape or component before any machining is completed. With high wear items this is a vital component to increase life of that component, though the tradeoff is they are usually a throw away piece once their useful life has been went through.  

Ceramic Matrix Composites (CMCs)
Ceramic matrix composites (CMCs) consist of ceramic fibers embedded in a ceramic matrix, offering exceptional thermal stability and resistance to high temperatures. Typical oxide and non-oxide CMCs usually consist of alumina, zirconia, and silicon carbide components. These types of materials provide a high strength value that lend them to be used in automotive and aerospace applications. Increasing the temperature resistance to failure provides for a greater range of uses in things like turbochargers, brake components and internal engine components. The market for purpose-built material that has a long wear resistance is key to making a vehicle that can withstand years of use. Like other composites, the cost of developing these materials is coming down to the point that are being utilized in a mass production situation unlike in the past. Offsetting the cost by utilizing the weight reduction to increase efficiency, these types of materials provide a path to a more sustainable automotive future.  

Conclusion
Composites are revolutionizing the automotive industry by enabling the development of lighter, stronger, and more sustainable vehicles. The use of carbon fiber composites, glass fiber composites, natural fiber composites, hybrid composites, and other advanced materials is transforming vehicle construction and performance. As the industry continues to evolve, the demand for innovative composites is expected to grow, driving the future of automotive design and engineering. From finding new materials that can be repurposed as vehicle components to developing new elements, the creation of new technologies will press on as the world continues to evolve. As the technician and training programs proceed, they will have to adapt to the changing demands of the OEMs in the ever quest of increasing performance while reducing energy consumption. Working with these materials in the Collision and Repair fields will require those technicians to increase their knowledge of how to handle these components. From understanding how thermal dynamics affect their operation to what is the expected life of the materials, all of these items must be taken into consideration when repairing failures. The desire for a vehicle with unlimited range, great crash performance, in-demand styling and ease of manufacturing will continue to push the envelope to the next thing. 

The MAST series of CDX provides the instructor pointed material to exceed the requirements of any ASE training currently on the market. Utilizing the Read-See-Do model throughout the series, the student has various learning modalities present throughout the products which allows them to pick the way they learn the best. From developing simulations on cutting edge topics to providing a depth of automotive technical background, CDX has a commitment to making sure instructors and students have the relevant training material to further hone their skill sets within the mechanical, electrical and software driven repair industry. CDX Learning Systems offers a growing library of automotive content that brings highly technical content to the classroom to keep you and your students up to date on what is currently happening within the Mobility Industry. Check out our latest title Light Duty Hybrid and Electric Vehicles, along with our complete catalog Here. 

References
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About the Author
Nicholas Goodnight, PhD is an ASE Master Certified Automotive and Truck Technician and an Instructor at Ivy Tech Community College. With nearly 20 years of industry experience, he brings his passion and expertise to teaching college students the workplace skills they need on the job. For the last several years, Dr. Goodnight has taught in his local community of Fort Wayne and enjoys helping others succeed in their desire to become automotive technicians. He is also the author of many CDX Learning Systems textbooks, including Light Duty Hybrid and Electric Vehicles (2023), Automotive Engine Performance (2020), Automotive Braking Systems (20219), and Automotive Engine Repair (2018).