BASF, ContiTech develop fiber-reinforced engine rod

BASF and ContiTech Vibration Control have developed what is said to be the first plastic engine torque rod, molded of fiber-reinforced polyamide for the Opel Vectra and Saab 9 3.

BASF AG (Mannheim, Germany), in partnership with ContiTech Vibration Control (Hannover, Germany), a division of Continental AG, has developed the first engine torque rod made of plastic that can withstand high mechanical loads.

The rod, which has gone into serial production for the Opel Vectra and Saab 9 3, is manufactured from glass fiber-reinforced polyamide (PA), using BASF's Integrative Simulation (IS) process to ensure the part is able to withstand the harsh environment in which it works.

The engine torque rod functions to secure the vehicle engine and transmission assembly, as well as to damp vibrations and to insulate structure-borne noise. Conventionally, components such as this have been made from either steel or aluminum. BASF's new torque rod is made from PA grade Ultramid A3WG10 CR. By using plastic, the part weighs 35 percent less than its aluminum predecessor, the company says.

The engine mount system, which the torque rod is part of, is the primary connection member between the engine/transmission unit and the automobile body. In addition to high loads, these systems are exposed to temperatures ranging from –30°C to 120°C (–22°F to 248°F), and contamination by oils and other chemicals.

Traditionally, automotive engineers had thought it impossible to use thermoplastics for parts that are subject to such high mechanical loads. In order for BASF to create its PA component, the company had to design high-quality material models, powerful simulation tools (IS) and develop specialist materials, such as Ultramid A3WG10 CR. The PA is part of the company's Ultramid CR range. The structural properties of these resins depend on precisely determined fiber orientation and strain rates.

BASF also says the performance level of these plastics is higher and the standard deviation of the mechanical properties is smaller than with other commercially available PAs, BASF says. Moreover, feedstocks are accurately selected and production conditions are strictly controlled so that components made of these plastics offer a constant quality level and calculations of their properties closely match manufacturing requirements.

According to the company, the most important part of the development – calculation of component properties and simulation of the part – was based on BASF's IS instrument, which was updated to carry out these functions for the torque rod. The method is widely used in industry for part dimensioning - a strength calculation is carried out independently of the process simulation using only averaged characteristic material properties. However, in order to better use the capabilities of fiber-reinforced PA, it was necessary to correctly account for fiber orientation at various places in the part, since mechanical properties differ substantially as a function of the fiber alignment. The IS process was able to link the results of the filling simulation with a finite element analysis in which the fiber orientation throughout the part was taken into account.

These findings, along with the influence of the temperature and the load rate, were then used for dimensioning the component and the mould. Complex life cycle tests, as well as the final vehicle testing of Adam Opel AG, have shown that IS yields a reliable component design, BASF says.