A robot arm presses onto the side bolster of a seat 10,000 times. The engineers at Audi subject every seat to numerous stress tests before it goes into series production. But what are these tests like, and how is a seat developed at Audi? Let us pay a visit to the Audi seat engineers.
He strokes his arm almost tenderly over the softly padded skin. Over and over again. 10,000 times in total. But before you get the wrong idea: we are not talking about a romantic film scene, but rather a tough stress test on a seat, thousands of which are installed in Audi cars. In this so-called entry/exit test, a robot arm with a rubbing cloth rubs over the side bolster of the seat to test whether any stitching comes undone or any foam crumbles away.
At Audi Seat Development in Ingolstadt, a team of engineers tests all new seats before they go into series production. And months before the stress limits of the seat are tested, the seat engineers at Audi start work on the perfect new seat.
Step 1: The seat structure
Two years before endurance testing. Florian Engstler, engineer at Audi Seat Development, broods over his desk. His assignment: to develop a new seat, together with his colleagues. Next to him is a thick catalogue. “The function catalogue is given to us by Sales. That tells us which functions the new seat should have,” explains Engstler.
The scope of functions of the new seat should leave no wish unanswered. Lumbar support, seat heating, numerous adjustment options, variable side bolsters, ventilation, massage function. “We put a lot of technology into our seats for these functions. The first step is to decide what type of seat structure we want to use – what type of ‘skeleton’, if you like,” Engstler continues. “The seats are structured in a modular manner. After each project, we configure the appropriate structure from the modules.”
Step 2: Planning the comfort surfaces
The development team configures a seat structure that allows enough space for the technical fittings inside the seat. The next step is to plan the comfort surfaces. Before the Design department can start its work, the development team has to answer the following questions: How wide should the backrest and the seat cushion be? How do we want to shape the side bolsters? How do we want to design the head restraints? “To guarantee comfort, we work out a design specification at the very beginning of the development process,” Engstler tells us. “The design team then orientates its work around these specifications.”
The width of a seat is a particular challenge for the Audi developers as this cannot be adjusted. “A seat for everyone. That is the goal. To ensure that just about everyone feels comfortable in the seat, we make use of data from research literature in which many different people have been measured,” Engstler continues. Furthermore, a large number of Audi employees also test the seat on special test drives, and they give their feedback to the Seat Development department. The dimensions for the new seat are derived from this feedback, the research results from literature and experience gained in earlier projects.
It is in this stage of development that the “hip point” comes into play. The so-called “H point” is a calculated point that describes where a person’s hip will be when they are sitting in the vehicle. Factors that depend on this include head clearance and the ease with which controls can be reached.
Step 3: The strake process
The most important framework conditions have now been clarified: seat structure, comfort surfaces and H point. The so-called strake process begins after the Design department has prepared an initial design with these specifications. In this process, experts from Design, Development and Quality Assurance meet and combine the specifications and ideas of the different departments. “The strake process effectively forms the link between design and engineering,” Engstler explains.
“The greatest challenge is to reconcile the different technical, quality and production requirements.” The strake process covers several rounds in which the details of the seat become ever more concrete. The engineers then construct the first individual components and build the first prototypes. These are tested on numerous test drives. Data is gathered and the seat is continually developed until it is ready to take the stress tests.
Step 4: The stress tests
This is where the seats face their first really hard tests. First of all, the engineers place the seat in a darkened room and test it one last time before it disappears behind a heavy metal door. Little by little, the temperature in the room is increased until an oven-like 90 degrees is acting on the seat. Not long after that it starts to get frosty as the engineers turn the temperature down to minus 30 degrees. “In the thermal test, we subject the seat to extreme temperatures to find out how the material responds. At very low temperatures, the material could become brittle,” Engstler explains. In addition, this test also tells the engineers how long it takes for the seat heating to reach the required temperature in such cold conditions.
In the next station, a robot arm repeatedly presses onto the surface of the seat cushion to simulate intermittent stress such as that caused by a person’s knee. This enables the engineers to test whether the surface of the seat can withstand the rubbing and whether the intermittent stress damages the seat heating. “Besides the endurance tests, there are also safety tests. We test different crash scenarios to find out how the dummy sits in the seat and how the head restraint performs,” Engstler continues.
After a development time of 42 months and numerous endurance tests, it is done! The seat can go into series production.