GAMING

ESI Group announced today the successful completion of Renault’s first ‘fully virtual’ preliminary design of a new seat using PAM-COMFORT, ESI’s advanced solution for Virtual Seat Prototyping.

“Using PAM-COMFORT, within a short period of time, and with few resources, we were able to deliver a new seat design meeting our objectives,” said Mr Jérôme Makala, Head of Comfort and Safety Research Department, Renault Group.

ESI’s PAM-COMFORT software offers a scalable, innovative and customized solution dedicated to virtual manufacturing and virtual testing (static and dynamic) of the soft parts of a seat. Virtual Seat Prototyping consists of several chained simulated steps ranging from seat manufacturing, occupant static seating, to occupied seat NVH (Noise, Vibration…) - where the stresses resulting from each step are needed for the next one. The chaining is a necessary requirement to accurately predict the behavior of the seats under numerous loading conditions (trimming, dummy loading, various human anthropometries, and vibrations) and for various design changes (materials and shape).

At Renault, where the full Virtual Seat Prototyping methodology is being deployed, one important step after the preliminary design of a new seat model is the virtual testing of the dynamic comfort performance using PAM-COMFORT.

Dynamic Comfort Testing

In order to accurately predict seat comfort, Renault runs a dynamic test of seat transmissibility with a static weight. The test helps evaluate the seat frequency response and thus informs Renault about how the seat contributes to the vertical acceleration filtering of the car, which is of first importance to dynamic seat comfort. This test is used improve and validate the seat design.

Seat and vibration modelling

Renault simulated this test procedure with a Finite Element calculation using PAM-COMFORT.  After completing the seat manufacturing simulations, a dummy is imported in the model to launch the computation. This calculation is divided in two phases: first, a static phase where the dummy is seated and where the equilibrium is computed to precisely know the stress and strain states of the various parts of the seat; second, a dynamic phase where a vertical acceleration signal is applied to the seat rail to obtain the seat dynamic transmissibility at the interface with the dummy.

Seat dynamic transmissibility

Computed results showed a very good level of correlation with physical tests, therefore confirming the validity and predictability of both Renault’s simulation modelling and the methodology applied.

“This simulation input can truly be considered as an “ultra realistic” model, since it allows the simulation of the whole complex mechanical phenomena of the seat, the non-linearity of the materials, the large displacements of the cushion foam and springs, as well as the effect of the cover trimming”, declared Mr Jérôme Makala, Head of Comfort and Safety Research Department, Renault Group. “The developed models and methodology enable the computation of predictive results, using only physical parameters and without any tuning of filtering. This good correlation between simulation and test results confirms the ability to assess the riding seat comfort in a full virtual process.”

As they are very satisfied with the results of the first "fully virtual" process with PAM-COMFORT, Renault has started the process of transferring this methodology to its seat providers and to Nissan.

Visit our website www.esi-group.com/products/comfort to find out more about PAM-COMFORT applications and benefits.