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Designing safety and comfort into seats

The SED project developed an advanced concurrent engineering platform which can reduce the design times of new concept seats for next generation cars. Bringing together numerical database methodologies with experimental techniques, including a specially developed dummy to evaluate vibrational behaviour and a side impact sled for passive safety tests, time-to-market for new ultra-light and comfortable seats is being reduced. In addition, the project provided the basis for expressing seat comfort and safety in terms of measurable parameters ('norms'). The platform's feasibility was demonstrated with a successful validation test and the Lear Corporation is actively using the platform to design seats for a number of car makers.

Some areas of car design, while using sophisticated computer-based and experimental techniques, also have to use time-consuming and expensive trial and error methods, and rely on subjective human opinion. The car seat, which can significantly reduce fatalities and injuries in accidents and is the single most important factor in determining quality of life in a car, is one such example.
A seat has to guarantee proper conditions for the human body in terms of passive safety and comfort, meet medical criteria, legislation and customer needs, as well as meet requirements for recycling at the end of its life. In the past, seat design methodologies tended simply to follow the law and the designer's idea of comfort. This was both an inexact and lengthy process because ensuring the specific criteria were met required extensive prototyping and there was no mechanism by which all the design phases could be run in parallel.

New processes address weaknesses

As the complexity of seat designs increases, with added features, improved safety levels and improved integration with overall vehicle design, the Seat Evaluation and Design (SED) project aimed to integrate experimental and numerical methods into a single, dedicated seat design process. With a total annual market in Europe for car seat kits of over 5,000 MECU, the anticipated impact of such a process would be tremendous.
This engineering platform covered the design, evaluation and testing phases and as well as including traditional physical approaches, it also aimed to integrate 'virtual' techniques such as computer modelling and simulation. In developing the platform, which would include design databases, Computer-Aided Engineering (CAE) tools and specific design methodologies, the project members focused on five key areas.
In looking at passive safety, Berlin University and the Fiat Research Centre (CRF) focused on evaluating the response of seat and occupant to side impacts, using an experimental sled test and a specially developed dummy. These results were used to develop a simulator to help predict results for other crash conditions.
Courtaulds Textiles Automotive Products looked at the objective evaluation of thermal comfort, assisted by Loughborough University. This included analysing the factors influencing thermal comfort, establishing the relevant design criteria and developing methods for correlating subjective assessments to actual trim characteristics.
In the area of ergonomics and posture, Loughborough University, with assistance from CRF, developed a suite of tests to improve the predictive performance of individual sets of measurements. Information on the influence of car seating on musculoskeletal diseases and factors influencing postural position were combined, to provide a simulation of the man-seat interaction.
CRF, with help from Southampton University, looked at developing procedures for ride comfort analysis, including the design of a new 'anthropodynamic' test dummy which very closely followed the physical reactions of a normal person to vibration. Using this dummy, along with new vehicle test procedures and data reduction methods specific to seat comfort evaluation, they defined standard seat vibrational characteristics. From this, factors influencing vibrational comfort could be assessed and vibrational criteria defined for the foam padding. This work, done by the Lear Corporation, significantly increased vibrational comfort.
With growing concern for the environment, Lear also developed recycling recommendations. Their main focus was on foam selection, based on a compromise between recycling, and safety and comfort. They also assessed strategies for the whole seat design including dismantling techniques and re-use constraints and opportunities.
Whether to use physical or numerical techniques for each phase was determined by engineering complexity and cost-effectiveness. In general, the team used experimental procedures where possible, with numerical techniques adopted only when offering results more quickly or cost-effectively.

Bringing everything together

Merging all these procedures into a single engineering platform which allows all the development sub-processes to be run concurrently was a primary goal - with seat design phases traditionally run sequentially, the biggest reductions in time-to-market would be achieved by allowing all the processes to proceed together. Lear, in cooperation with the Universities, developed software procedures for concurrent management of the engineering process, beginning with a target setting phase for the development of a new seat and going right through to completion of the product release phase and the start of production.
At this point, Lear also integrated into the platform a database of results from the reference tests with information on seat design and analysis, which helps in predicting the behaviour of new seats without having to develop a dedicated prototype.

Establishing standards

The engineering platform has also resulted in a deeper understanding of seat performance in relation to total car design which in turn, has allowed the team to define initial criteria for establishing 'norms' for seat safety and comfort. Once adopted, such norms hold the promise of increasing the overall well-being of the automotive user, as well as ultimately reducing social costs due to injuries and diseases.
The three universities involved in the project in fact each have specialist areas where they are responsible for establishing standards and norms: Berlin for passive safety and side impact; Loughborough for postural comfort; and Southampton for vibration and comfort. New proposals in each of these three areas emerged from the SED project and the universities are currently promoting these new standards to the appropriate bodies.

Results for the real world

From the outset this project had a built-in validation phase, involving the design of a new seat structure made of magnesium, as well as a seat with integrated belts. Using the new platform, the project achieved reductions of around 30% to 40% in the time needed for the individual design processes, resulting in about a 25% reduction in the overall seat design process. There is also an increase of development productivity which, as seats continuously become more complex, allows more advanced seats to be designed with no increase in cost.
One of the project partners, Lear, has business units dedicated to individual car makers and until recently, all Lear's seat development was done in the US. However, since the successful validation phase, their European Research Centre in Turin has been using the platform to aid seat development and testing for all its business units. Another partner, Courtaulds, is using the thermal comfort and recycling results from the project to design new car seat fabrics.

Europe in the driver's seat

As these results clearly show, the enhanced co-design capabilities achieved are strengthening integration between car makers and SMEs in Europe. The Concurrent Engineering process is also putting seat makers and suppliers in a better position to face strong global competition, a major characteristic of the automotive industry. In fact, the project has been so successful that through a formal bilateral cooperation, CRF and Lear are continuing and extending the scope of the project beyond its original objectives, to look at new methods for evaluating seat performance in terms of seat lifecycle. And in the next phase, CRF will be looking at integrating all the results of the European project's engineering platform, using the upcoming generation of parametric and associative CAD tools.


Project Title:  
Advanced technologies for automotive seat evaluation and design

Industrial and Materials Technologies (BRITE-EURAM/CRAFT/SMT)

Contract Reference: BE-5549

Cordis DatabaseFor more information on this project,
go to the CORDIS Database Record