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Bye bye sheet metal: VW Golf front-end carrier is made solely from plastic

Just say "no" to sheet metal. The front-end carrier in the new Golf 7 is completely made from plastic.

This makes the part that owes its shape to elaborate calculations and simulations one of the world's first front-end carriers without metal reinforcement.

A front-end carrier without metal reinforcement has gone into production at Volkswagen as an all-plastic injection molded part. The part is installed in the new Golf 7 and consists entirely of Ultramid B3WG8, a polyamide from BASF. [Photo: BASF]

 

 

Replacing the previous polypropylene hybrid part with an all-plastic part required the use of not only Ultramid B3WG8, a highly reinforced polyamide during development, but particularly ULTRASIM, a CAE tool that helps automotive customers create virtual product prototypes and optimized (multi-material) designs that result in finished mass-produced components with marked weight and cost improvements. The sheet steel parts that had been attached to previous VW Golf front-end carriers are now eliminated. This reduces the weight of the front-end module significantly compared to that of the predecessor model, saving assembly time and costs. Volkswagen produces the part in-house.

In addition to limited space for installation, the requirements for the all-plastic part included a variety of very challenging load cases, including static and dynamic hood latch failure, where incorrect opening and closing of the engine's hood is simulated and tested under the harshest conditions. At the same time, the stiffness and vibration behavior of the system comprising front end and radiator was optimized on the basis of CAE analyses and validated in an actual vibration test.

Special attention was also devoted to the crash sensors attached to the front end. They ensure deployment of the airbag at the right moment in the event of a head-on collision. For this, the plastic part must exhibit a certain dynamic stiffness at a defined location and satisfy the automaker's crash acceleration requirements. In a real-world test, the vibration response of the part corresponded exactly to what was designed and predicted by ULTRASIM: the Ultramid front-end carrier transmits the collision signal correctly.

Using Ultramid plastic and the ULTRASIM CAE tool
The primary load cases provide the basis for a front-end design; from these, an optimized topology is derived. This topology gives the designer valuable information regarding the final shape of the part. Thanks to the highly accurate predictions of ULTRASIM, only slight modifications were needed in moving from the prototype of the front-end carrier to its serial production. This demonstrates the kind of challenging applications that can be addressed by combining a suitable material with the correct prediction and calculation tools.

Furthermore, ULTRASIM, together with its special failure models, can be integrated seamlessly into the calculation environment for the automaker's entire vehicle. This requires, however, that very specific data, such as crash-relevant material data for the plastic, is available to describe the exact effects of temperature, moisture, and rate of load application. A simulation is preceded by acquisition of this extensive material data from experiments conducted with the aid of complex testing and measuring instruments. The simulation tool is then able to predict failure behavior, strain rate dependence, and even tension-compression asymmetry as a function of fiber orientation.

Source: BASF

Published March 2013

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