German automaker Audi plans to  introducing new, lightweight suspension springs made of glass fiber-reinforced polymer (GFRP) in an upper mid-size model before the end of this year.

The GFRP spring, which Audi developed in collaboration with an Italian supplier, is light green, the fiber strand is thicker than the wire of a steel spring, and it has a slightly larger overall diameter with a lower number of coils. However, it is some 40 percent lighter.

The core of the springs consists of long glass fibers twisted together and impregnated with epoxy resin. A machine wraps additional fibers around this core - which is only a few millimeters in diameter - at alternating angles of plus and minus 45 degrees to the longitudinal axis. These tension and compression plies mutually support one another to optimally absorb the stresses acting on the component. In the last production step, the blank is cured in an oven at temperatures of over 100 degrees Celsius.

Whereas a steel spring for an upper mid-size model weighs nearly 2.7 kg (6.0 lb.), a GFRP spring with the same properties weighs approximately 1.6 kg (3.5 lb.). Together the four GFRP springs thus reduce the weight by roughly 4.4 kilograms (9.7 lb.).

"The GFRP springs save weight at a crucial location in the chassis system. We are therefore making driving more precise and enhancing vibrational comfort," said Dr. Ulrich Hackenberg, Member of the Board of Management for Technical Development at AUDI AG.

The GFRP springs can be precisely tuned to their respective task, and the material reportedly exhibits outstanding properties. It does not corrode, even after stone chipping, and is impervious to chemicals such as wheel cleaners. Last but not least, production requires far less energy than the production of steel springs.