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
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.
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
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
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