Published on September 10, 2015
As seen on Examiner.com.
Today’s automakers have a common objective: To reach the government-mandated CAFE (corporate average fuel economy) goal of 54.4 miles-per-gallon for light-duty vehicles by the year 2025. Increasing the fuel efficiency in cars by decreasing their weight is critical to meeting this goal.
Plastics’ Role in ‘Lightweighting’ Vehicles
Plastics and plastic composites have been demonstrated to be effective materials when it comes to “lightweighting” vehicles. This is because plastics account for approximately 50 percent of the volume of a typical vehicle, but only 10 percent of its weight—and reduction in weight can play a significant role in lowering fuel use. Fuel efficiency is estimated to go up 6 to 8 percent for every 10 percent of a vehicle’s weight that is cut.
But reducing weight is only one of the benefits that extensive use of plastics and polymer composites provides when it comes to today’s new cars. They also can improve vehicle safety.
Plastics are Helping Save Lives
From front and rear bumpers to side doors and seat belts and airbags and dashboards – and even drive shafts – plastics and composites have contributed greatly to the safety of today’s vehicles, helping save thousands of lives every year.
A study by the National Highway Traffic Safety Administration (NHTSA) reported that innovative safety technologies, many of which included the use of plastics and composites, saved an estimated 613,501 lives between 1960 and 2012. A study by the Insurance Institute of Highway Safety showed that driver deaths dropped to 28 per one million from 87 over the period from 2002 to 2011 as safety features advanced.
In addition, research by the Rocky Mountain Institute indicates that a lighter vehicle that is large and better designed can have crash safety comparable to, or better than, that of a similarly sized heavy vehicle. Such studies help dispel the myth that a lighter vehicle is inherently less safe than a larger, heavier one.
Safety Starts up Front
Lightweight plastics used in the front of vehicles can absorb energy from an impact by creating a “crumple zone,” effectively acting as a cushion to protect the occupants of the vehicle inside. In a collision, the crumple zone can collapse like an accordion to lessen the impact on the occupants.
Until the 1950s, people believed that the more rigid a car’s body, the better protected its passengers were. That changed in 1953 when, thanks to the research and work of a company engineer named Béla Barényi, Mercedes-Benz introduced the first car to feature a crash-stable floor assembly. This design improved safety for the occupants in the event of front or side crashes. By 1959, the German automaker was incorporating front and rear crumple zones into all of its sedans.
Today, a crumple zone in the front and sometimes the rear – coupled with a rigid passenger – compartment are an integral part of the design of every new car. And plastics and composites provide an effective material for use in crumple zones because they collapse on impact.
Beyond the Crumple Zone
The benefits of plastics and polymer composites go far beyond their use in crumple zones, however.
Lightweight plastic foams used to fill hollow structures such as pillars, cowls, and rocker panels can add to the structural strength of vehicles, helping increase protection for occupants in the event of rollover crashes, the most deadly crashes of all. (According to the federal government, rollovers have a much higher fatality rate than any other kinds of crashes. Of 9.1 million passenger car accidents in 2010, only 2.1 percent involved a rollover, but they accounted for nearly 35 percent of the deaths.)
Auto racing engineers realized the benefits of plastic composites in both safety and efficiency years ago, but cost and other factors limited the use of these materials in mainstream passenger cars. Today, new and innovative techniques that cut the production costs of these composites make their use more feasible. The forecast is that the use of plastics, including composites, in automobiles will increase 75 percent by 2020.
Use of plastics in auto glass not only can trim a vehicle’s weight, but also help prevent injuries to passengers caused by shattering glass. Most windshields today are made from laminated glass with a thin plastic layer between two sheets of glass. Laminated glass can bend slightly upon impact and is less likely to shatter than normal safety glass, helping reduce the risk of injuries.
Plastics also can play a part in the power train of a vehicle. Composite drive shafts made of carbon fiber and plastics can break up into small pieces in the event of a crash, helping eliminate the threat of a puncture into the cabin’s interior. Composite shafts also have been demonstrated to be more efficient in delivering more power to a vehicle’s rear wheels.
Plastics and composites have a vital role in the safety features inside the cabin as well. NHTSA reports that polyester fiber seat belts saved an estimated 12,584 lives in 2013, and the government credits nylon fabric frontal air bags with saving 25,782 lives between 1987 and 2008.
With the continuing pursuit of getting more miles out of a gallon of fuel, carmakers will go on to seek more ways to trim pounds from passenger cars and trucks. Plastics and composite materials provide new and innovative ways for them to reach that goal while meeting the public’s demand for more safety features in today’s cars.