- First use of GMT (glass-mat thermoplastic) composite on bumper
- GMT bumper of 1984 Corvette Sports named 2015 Hall of Fame winner by SPE
- The history of the GMT bumper
The first use of glass-mat thermoplastic (GMT) composite on the front bumper of the 1984 model year (MY) Chevrolet Corvette sports car from then General Motors Corp. (GM) has been named the 2015 Hall of Fame winner by the Automotive Division of the Society of Plastics Engineers (SPE).
The first GMT bumper explained
“GM’s first use of a GMT bumper on the 1984 Corvette involved a number of firsts,” says David Reed, General Motors Corp.-retired. “This twopiece, compression-molded, induction-welded, box-section design used Azdel PM 400 40% continuous-strand, randomly oriented glass fiber in a polypropylene matrix from PPG Industries. The application, which was molded by LOF Plastics Inc., also represents the first use of EMA weld1 welding.”
1984: GM commercializes Corvette GMT bumper
Shortly after the Corvette bumper was commercialized, GM launched C-section GMT designs on the front bumper of the D-body platform, which included models like the Cadillac DeVille, Fleetwood, and Brougham sedans. The GMT beams were mounted to the car frame using ACDelco shock absorbers, which further increased the impact energy the beam could absorb.Another C-section design was used on Cadillac Seville sedan. This design incorporated a single in-turned upper flange, a development that later led to the creative use of a double in-turned flange on models from Oldsmobile.
1986: GMT bumper moves to Ford
By 1986, GMT bumpers had moved to Ford Motor Co. and were featured on the front bumper of the Ford Mustang sports car. These GMT beams were mounted using Ford’s polygel mitigators (PGMs) Two years later, GMT bumpers were used for the first time on the rear of the Ford Continental DN9 sedan as well as the front of GM’s N-body cars. The latter were notable for being the first compression-molded beams with two in-turned flanges, which were notoriously challenging to mold.
1989: Honda uses C-section GMT bumpers on Honda Accord
In 1989, Honda Motor Co. used C-section GMT bumpers on both the front and rear of the Honda Accord compact cars produced in North America and Japan. Not only were these the first non-Big 3 use of the material/application, but they also were the first GMT beams combining both unidirectional and randomly oriented continuous glass mats, and the first composite beams that were hard mounted to vehicles (fixed directly to the rail beams without the use of shock absorbers).
1990: GMT bumper features “peekaboo” stainless steel, in-molded chrome strip
By 1990, GM used GMT bumpers on the front of the Buick LeSabre sedans, which featured a “peekaboo” stainless steel, in-molded chrome strip. The Japanese automakers were back in 1991 with GMT bumpers on multiple mid-size models produced by Toyota Motor Corp., Suzuki Motor Corp., Nissan Motor Co. Ltd., and Mazda Motor Corp. During the 1990s, over 16% of all passenger cars globally sported GMT bumper beams, consuming over 500-million pounds/226,796 tonnes of the material.
1998: GMT bumper uses discontinuous chopped-fiber mat
Another design evolution occurred in 1998 with the development of the I-beam, which was the first GMT bumper to use a new discontinuous chopped-fiber mat because it was better at penetrating deep into the complex rib structures that distinguished this beam. So novel was the design that it won the 1998 SPE Automotive Innovation Awards Competition’s Grand Award and it also was cited by the Insurance Institute for Highway Safety (IIHS).
2000: Korean Hanwha developing GMT beams for all Korean passenger car models
By 2000, South Korean GMT producer and AZDEL licensee Hanwha was developing GMT beams for all Korean passenger car models and the company still supplies to these OEMs. GMT bumpers also proliferated on vehicles produced by European automakers. In France, PSA Peugeot Citroën Group used GMT with randomly oriented continuous glass and unidirectional continuous glass reinforcements on front bumpers of Peugeot 309 sedans from 1986 to 1992. GMT combining mats of chopped glass and glass fabric (laid up 0°/90°) moved to rear bumpers from 1995-2002 on vans from PSA (Peugeot 806 and Citroën Evasion) and Italian automaker, Fiat Group (Fiat Ulysse and Lancia Zeta).
2004: Rear GMT beams move to PSA cars
Rear GMT beams moved to PSA cars in 2004 on the Citroën C5 (random glass mat) and Peugeot 407 sedans, and Peugeot 407 SW wagon (random plus fabric mats). Versus steel, the incumbent bumper beam material at the time, GMT composite beams offered a number of benefits, including 30% lower weight, greater design flexibility, lower tooling costs (especially beneficial for low-volume specialty models), elimination of rust/corrosion, and better impact performance (less vehicle damage) during low-speed impacts.
To be considered for a Hall of Fame award, an automotive plastic or composite component must have been in continuous service in some form for at least 15 years. On Wednesday, November 11, 2015, Ted Adamczyk, design release engineer at General Motors will accept the award on behalf of the original team that worked on the program at the 45th-annual SPE Automotive Innovation Awards Gala at Burton Manor in Livonia, Mich., USA.