Press Release
Page 1: Developing the concept
Page 2: Design
Page 3: Simulation and computing
Page 4: The "Strake"; Wind tunnel
Page 5: Electronics
Page 6: Test-driving; suspension
Page 7: A car for the senses
Page 8: Quality assurance
The “Strake�
On the Audi Q7, virtual reality also played a decisive part in an area that can be regarded as a link between the design and construction departments: the “Strake�. This term, which came originally from shipbuilding, now refers to the geometrical representation of all the vehicle’s interior and exterior surfaces that are visible to the customer – taking all technical and formal aesthetic requirements into account. The “Strake� therefore embodies the core competence for the finest surface finishes and the associated quality.
“We act as a bridge between design, that is to say the aesthetic statement made by the design model, and construction, representing the technical activities of the Vehicle Development departments�, says Horst Schneider, who is in charge of “Strake� visualisation. According to his records, between 600 and 800 components with relevant surfaces are “straked� for every project.
As the product range continues to grow and become more varied, but the time available for development work becomes shorter, systematic use of virtual techniques is essential as an error filter and an aid to decision-making in the process. Horst Schneider explains: “If we wish to make decisions possible at early stages in the development process, we shall have to integrate virtual reality even more strongly into our day-to-day “straking� activity in the future.�
Whereas previously only one digital data control model was processed in virtual form, today construction and visualisation data are networked during the very first discussions (design, “straking�, project, simultaneous engineering, technical team) and can thus be prepared photo-realistically and used for decision-making.
Schneider: “There are various degrees of preparation for visualising the “straking� process. For a discussion on the overall impression made by the vehicle’s interior or the body, the quality is naturally many times higher that during a normal working meeting where a rapid general view of an individual part is all that’s needed.�
The general impression, lighting simulation, surface diagnosis, colour variants, view through to the rear or the production of pictorial material for Marketing colleagues are just some of the activities undertaken with VR in the straking process.
Design Check
The Design Check is a kind of “barometer of maturity� during Audi Q7 development as a whole. It is a visualisation and decision-making process aimed at avoiding incorrect development steps and enabling clearly defined work instructions to be issued. The Design Check begins in the concept phase and continues until production starts. During this lengthy process, concepts and the current development-work position are visualised and verified at an early stage. The engineers operate both in visual worlds and with models, but also with “genuine� fully-functional vehicles.
The purpose of the Design Check is to render the complete Audi Q7 project transparent for everyone who is concerned with the vehicle’s development. Ergonomics and package dimensions, for example the door sills, legroom and headroom, loading through the tailgate, the view to the rear, the driving position and even the practicability of the cup holders can all be examined at an early stage during the Design Check.
This is also where all the necessary product optimisation measures are agreed with the specialist departments, with the aim of enhancing series-production development quality and, as a result, the quality of the finished product.
Wind tunnel
A great many specialist areas were – and are – directly involved in development of the Audi Q7 to series production readiness. The project acquired much of its dynamic character from the engineers concerned with aerodynamics and aero-acoustics. Audi Q7 prototypes and pre-production vehicles spent more than a thousand hours in the Audi wind tunnel centre in Ingolstadt, which is one of the most modern anywhere in the world. The results are a drag coefficient of 0.34, the best value in the large SUV segment, and extremely low wind noise levels.
For Dr. Michael Jaroch, who with his team was responsible for Audi Q7 aerodynamic, aero-acoustic and water management development work, achieving such good results was far from easy. As he says: “Optimum design of a vehicle of this size, without any adverse effects on its styling, is a difficult balancing act for us.�
The Audi development engineers studied the airflow acting on the Audi Q7 in a vehicle wind tunnel that is both quieter and faster than those currently in use anywhere in the world. A turbine approximately four metres in diameter, with a drive rating of 2.6 Megawatts, delivers air to the wind tunnel at up to 300 kph.
The thermal wind tunnel is used to optimise the flow of air to the Audi Q7’s cooling systems. On this hi-tech test rig, the temperature can be varied anywhere between 20 and 50 degrees Celsius, and the airflow accelerated up to 275 kph. Even the floor of the measurement zone can be heated, to simulate hot road surfaces. Set into the floor is an additional roller for Audi models with quattro four-wheel drive.
A further development priority is water management. The aim here is to minimise interference with the driver’s view of the road as a result of dirt and water on the windows.
Dr. Jaroch illustrates this as follows: “Critical situations can for example arise if the car is following a truck along a wet road, and water spray from its wheels obscures the driver’s view. This can typically occur at speeds of between 70 and 90 kilometres per hour. Our aim in the case of the Audi Q7 was to optimise the airflow round the A-posts and exterior mirrors so that the side windows and mirror glass remain clean.�
How is this achieved? The vehicle is sprayed with a fluorescent liquid in a special wind tunnel devoted to surface contamination. Under black light, the paths taken by rain and spray and the areas where the water collects can be clearly seen.
