New Citroen C3 Features Lightweight Seat Structure

A lightweight seat structure from JSP offering a 2.2kg reduction in weight and increased levels of 'perceived quality' has been launched in Citroen's new C3. Engineers replaced the heavy and costly steel structure with JSP's Arpro, a strong, light and recyclable material. Material properties such as deformation resilience and moulding accuracy enabled Citroen to achieve improved alignment with visual design features such as leather stitching.

Paul Compton, JSP's president and chief executive officer in Europe, said: 'The objective was to create a lighter seat that could achieve excellent crash-test results. 'In prototype form, Arpro reacts in the same way as mass-produced components. 'This allowed us to create applicable parts quickly and without tooling. 'For a very small investment and within a short timeframe, we were able to validate and prove the concept in a real crash test.

'This gave the programme engineers the confidence to back the project for mass production,' he added. Arpro is strong and resilient enough to replace the metal anti-submarining ramp, which is there to help retain rear-seat passengers in their seats in the event of a vehicle collision, contributing to a simpler and lighter vehicle structure. Compared to the previous-generation C3 rear seat, switching to Arpro provided Citroen with a metal weight reduction of 1.79kg.

The balance of the saving is achieved through lower polyurethane content and a simpler fastening system; the latter serves to lower the assembly cost. Perceived quality has also been improved with the new seat design. This latest project follows on from other seating projects with Volvo and Daimler and applications for other global original equipment manufacturers such as interior trim, sun visors and impact protection products.

JSP recently completed a study to highlight the environmental benefits of using lightweight seating cores. The results of calculating a comparative CO2 (global-warming potential) figure for the production of an Arpro seat core show that Arpro delivers an environmental benefit 12 times that of its impact. Assuming a vehicle lifetime of 100,000km, Arpro can enable a reduction in CO2 of 2.65g/km.

Vistagy Develops Seat Design Software

Vistagy has announced the release of Seat Design Environment 2009 (SDE), which provides an accurate 3D master model of the trim cover from the earliest stages of design to manufacturing. SDE enables seat cover manufacturers to bring flat patterns that have been altered with 2D editing software back into the 3D CAD model. This master model definition can be used to automatically update engineering and manufacturing data to create a faster, more precise process for delivering seat covers to market.

The traditional 2D-based seat trim cover design and manufacturing process requires a significant amount of translation and verbal communication to transfer data between numerous people and software packages. Creating documents, such as drawings, bills of materials (BOMs), cost assessments and sewing instructions, is a manual, error-prone task that requires frequent data re-entry. This traditional process is highly inefficient because there is no single master model containing all the most up-to-date information and, most importantly, there is no way to obtain timely design feedback.

Previous versions of SDE have always provided a way for data and documentation, such as flat patterns, costing information, sew reports and BOMs, to be automatically created from a 3D CAD master model. SDE 2009 enhances the master model by providing an environment integrated into commercial CAD systems where geometric and non-geometric information can be captured within a single 3D CAD model throughout the entire design process; from initial generation of flat patterns to final detail design as required for manufacturing. Now design and manufacturing engineers and their suppliers can efficiently create and modify seat trim cover product definitions and generate associated engineering data automatically for use throughout a company and its supply chain.

SDE 2009 also provides enhanced capabilities for communicating design information, generating documentation, simulating producibility and defining seat covers. Engineering as well as manufacturing drawings can now be created with SDE 2009. This includes the ability to show and hide cutouts in drawings on sewing reports and engineering drawings as well as the ability to highlight colours on sewing reports to show seam types in isometric and flat pattern views.

This improves the communication of the designer's intent to the manufacturing team, speeding overall development time and increasing accuracy. With improved display of producibility results, the simulation can be inspected and used to identify issues that need to be addressed to make better flat patterns more easily. There are now more options for creating attachments (by centre point and length, by start and end points, and by point and length) and for creating manufacturing sew lines (by curve, attachment or backing pad).

Pam-Comfort Helps Renault Design New Seat

Renault has used ESI's Pam-Comfort system for the preliminary design of a new seat. ESI's Pam-Comfort software offers a scalable and customised 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 and occupant static seating, to occupied seat NVH (noise and vibration), where the stresses resulting from each step are needed for the next one.

The chaining is necessary to accurately predict the behaviour 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, an important step after the preliminary design of a new seat is the virtual testing of the dynamic comfort performance using Pam-Comfort.

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 important for dynamic seat comfort. This test is used to improve and validate the seat design. 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 in which 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 is a dynamic phase in which a vertical acceleration signal is applied to the seat rail to obtain the seat dynamic transmissibility at the interface with the dummy. Computed results showed a good level of correlation with physical tests, therefore confirming the validity and predictability of both Renault's simulation modelling and the methodology applied.