In the world of super deluxe luxury sedans Audi A8 has always been a bit of an underdog. It’s a fantastic car, but anyone willing to blow upwards of 100 grand on a sedan tends to go Bimmer, Benz, or Maser. So the A8 went in search of some sort of X factor to make itself special, and apparently it has found it in refined technicalities.
The first teaser for the new Audi A8 puts this in perspective revealing the car’s multi-material, lightweight space frame. It is a clever blend, made from a mix of aluminium, steel, magnesium and carbon fibre-reinforced polymer (CFRP). The main advantage is to optimally absorb longitudinal and transverse loads as well as shearing force, between six and 19 fibre layers are placed one on top of the other, ensuring a load-optimised layout.
Now for more technical details: A high-strength combination of hot-formed steel components make up the occupant cell, which comprises the lower section of the front bulkhead, the side sills, the B-pillars and the front section of the roof line. Some of these sheet metal blanks are produced in varying thicknesses using tailoring technologies – meaning they are customised – and others also undergo partial heat treatment. That reduces weight and increases the strength, especially in areas of the vehicle that are particularly critical for safety.
The aluminium components make up 58 percent of the new Audi A8 body, the largest share in the mix of materials. Cast nodes, extruded profiles and sheets are the elements characteristic of the ASF design. And here too the competition of materials has been driving progress. New heat-treated, ultra-high-strength cast alloys attain a tensile strength of over 230 MPa (megapascals). The corresponding yield strength in the tensile test is over 180 MPa, and for the profile alloys it is higher than 280, i.e. 320 MPa – significantly higher values than seen previously.
Rounding out the intelligent mix of materials is the magnesium strut brace. A comparison with the predecessor model shows that it contributes a 28-percent weight savings. Aluminium bolts secure the connection to the strut tower domes, making them a guarantor of the body’s high torsional rigidity. In the event of a frontal collision, the forces generated are distributed to three impact buffers in the front end.