Audi has showcased an advanced polymer spring, which is claimed to be 40% lighter than the steel equivalent. The new, lightweight suspension springs are made of glass fiber-reinforced polymer (GFRP), and will appear in an as yet unnamed executive class Audi model before the end of the 2014.
Developed in collaboration Italian Tier 1 supplier Sogefi Group, the springs are finished in a light green, and have thicker fiber strands and a slightly larger overall diameter with a lower number of coils than conventional items.
Whereas a steel spring for an executive class model weighs nearly 2.7 kilograms, a GFRP spring with the same properties weighs approximately 1.6 kilograms. Together the four GFRP springs therefore reduce the weight by roughly 4.4 kilograms.
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.