Helping Automobili Lamborghini create driveline concept design

Besides a breathtaking design, sporty driving experience and powerful explosion when pushing the throttle, customers expect to hear the brand’s characteristic sound when “all the horses” are released. 

Combining those prerequisites can be challenging. Although high-power generation leads to high internal torsional forces, and stable ride and handling calls for a stiff chassis, engineers have to make sure that sound does not become noise, and that the produced sound level complies with legislative requirements. 

Giacomo Papotti and Claudio Manzali, research engineers in the Lamborghini transmission department, witnessed the complexity of conflicting targets while designing the Lamborghini Aventador LB700-4 driveline. 

“Even the smallest noise that can disturb the driver needs to be avoided,” says Papotti. “Our test drivers experienced booming noise from the powertrain and a clunking noise from the gearbox while testing prototypes during the development
phase. The traditional way to solve such problems was by adding mass elements to change the eigen-frequencies, or by modifying support stiffness. 

“But increasing weight obviously has to be avoided at all times, and there is a risk of introducing new resonances. This manual process requires a lot of iterations and is very lengthy. Our mission was to find an effective simulation process to detect the root cause of noise issues and perform optimisation.” 

Insight through fast and correct modelling 

Being a satisfied LMS Test.LabTM software customer for many years, Lamborghini decided to use LMS Imagine.Lab AmesimTM software, also part of the SimcenterTM portfolio from Siemens PLM Software. LMS Amesim was employed to evaluate the torsional vibration response of the driveline to the cylinder pressures. 

“The pre-packaging of components helps a lot when modeling complex dynamic systems,” says
Papotti, “and the modularity of the software allows generating models with a complexity in function of the phenomena the user intends to investigate. Thanks to the availability of detailed dedicated libraries, users can efficiently create models that simulate real-life behaviour. 

“During the simulation, a few secondary variables, like the rotational speed of the gearbox shaft, were successfully correlated to measurements, giving us full confidence in the correctness of the model.” 

Generating a correct model in a fast and easy way is an important strength of LMS Amesim. The entire simulation model for torsional behaviour of the driveline can be created by ready-to-use components from the powertrain library, in addition to a few components from the mechanical design and signal control libraries. 

“The construction of the model was very easy because all building blocks were already there,” says
Manzali. “Only about 25 percent of our time went into the modeling. The remaining 75 percent was calibration work that includes defining all the parameters. Most of those were acquired by testing. We only sometimes needed data from suppliers. The data could easily be plugged into our LMS Amesim models.” 

Despite the rather simple model setup, the LMS Amesim simulation models were able 
to be used to provide Lamborghini with the necessary insight to solve the noise issues much more effectively than in the traditional way. 

“All parameters can be analysed during simulation,” says Papotti. “Batch simulation allows producing graphs for calculated values in function of the different parameters. This ensures fast, easy and detailed insight in the system’s dynamic behaviour. This efficient work is a real added value to our process and saves us a lot of
time. We can give more precise directions to our suppliers and save a lot of hardware loops. We have really succeeded at evaluating many more possibilities in a shorter time by using LMS Amesim.” 

The tool of the future 

With a successful introduction, Lamborghini engineers plan to continue using LMS Amesim. Both the model and results have been adopted by the entire Lamborghini research and development (R&D) department. 

“Owning a complete simulation model of the driveline is a huge added value to our development work,” says Manzali. “It will allow us to easily evaluate changes to the base model and can be used any time the market or legislation pushes us into a new challenge. 

“The true power of LMS Amesim is demonstrated by how easy it is to evaluate different driving conditions, software or hardware changes and even different configurations; and the speed at which those modified models give us correct results and trends.”