Vehicle Structures: A Mixed Bag

I drive a 2009 Honda Civic which I love. I’ve owned it for about eight years. When I bought it in 2014 it had 22,000 miles on it. It now has 202,000 and is still going strong.

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Comparing the 2009 Honda Civic to the 2022 Honda Civic will tell us a lot about where the automotive industry has gone to advanced materials in vehicle construction. The 2022 model, for example, has an aluminum hood and aluminum front and rear bumper beams. The front bulkhead assembly is made from a resin-based composite material; previously it was mild steel. The 2009 model had none of that.

Mixed materials

Vehicles are now a mix of materials: aluminum, ultra-high-strength steel, advanced high-strength steel, martensitic steel, boron, magnesium, plastic, carbon fiber, etc. the government’s Average Business Fuel Economy (CAFE) mandates. And now, with the emergence of electric vehicles, lightweighting is even more prevalent as automakers try to figure out how to extend range and battery life. In addition, advanced driver assistance systems (ADAS) have played a part in reducing weight. The more electronics you add, the more you increase the overall weight of the vehicle; somewhere, that weight has to come out. The answer so far has been lighter body materials.

Aluminum

As automakers continue to build stronger but lighter vehicles to save fuel, more and more aluminum will appear in vehicle structures. You will also see high tensile steel and ultra-high tensile steel, as these metals are also lighter but stronger, providing more protection for vehicle occupants. But aluminum will be by far the material of choice; it is the fastest growing automotive material and is expected to reach content levels of 514 pounds per vehicle (PPV) by 2026. Doors represent the highest net growth application of aluminum content per vehicle, with penetration reaching 30% by 2026. In addition, by 2026, the penetration of aluminum hoods is expected to reach 81% and hatchbacks/hatchbacks will reach 44%.

Smaller vehicles will most likely continue to have high percentages of high-strength steel, as it may not be beneficial to use more expensive materials, such as aluminum, carbon fiber and magnesium. With larger vehicles, the use of aluminum for weight reduction has more advantages in terms of manufacturing costs.

Everyone shivers when they hear the word corrosion. Corrosion protection has always been a major concern in making a vehicle last through the End of Life (ELV) of a vehicle, which is why the type of material used and its location are considered. A front steel bumper reinforcement would be subjected to a very corrosive environment, so an aluminum part might be more advantageous, due to its corrosion resistant properties. Better methods of combining dissimilar materials, such as steel and aluminum, have made hybrid construction much more feasible. It’s no longer just a choice; manufacturers have different options as to what they can use to achieve the desired results.

Repair recommendations

These different materials have different repair, fastening and welding requirements. The only way to know where these materials are and what they are is to access the original equipment manufacturer (OEM) repair procedures. Then you also learn the recommended repair method, if the repair is recommended. It may be recommended to replace the part, solder joint, adhesive joint, MIG brazing, spot welding, etc. The manufacturer may require a certain type of welder and welding wire. Performing the repair as you have always done in the past could jeopardize your livelihood, that of your employees and the lives of the occupants of the vehicle.

Summary

Materials will continue to grow and evolve when it comes to building vehicles. Shops should be prepared to identify these materials, their locations, and repair procedures recommended or required by the OEM. We can’t just assume that a part is made from the same material we were used to in the past.

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