Human models seating on aircraft passenger seats

5.1 Pressure distribution measurements

As defined in EN 4723, comfort measurement is a set of measures related to the seat itself (such as armrest top height over seat bottom cushion, cushion height above cabin floor level or average bed angle in full recline position), but also pressure distribution for several occupant postures. Usually volunteers are used to measure them.

But pressure mapping measurements performed with volunteers lead to two mains issues. The first one is the repeatability aspect of such experiment. Indeed, a pressure distribution is highly dependent on the anthropometry and weight, as well as the characteristics in terms of muscle tonus (flesh stiffness). As a consequence, the same individual should perform the tests in order to enable comparisons between seats. Additionally, for a given individual, a change in posture will dramatically affect the pressure distribution.

The second main issue regarding tests with volunteers is the subjectivity. The comfort/discomfort notion is highly subjective and such subjectivity doesn’t leave the possibility to do fair benchmarking between seats. It is therefore necessary to relate the objective pressure distribution measurement to this subjective feeling. Such connection has been established (MERGL et al., 2006).

5.2 Seating simulation of human models

The human models previously described (disabled, elderly and overweight human models), are used to simulate their seating in aircraft economic class seat, and to compare the induced pressure map. First a virtual seat model of a Zodiac seat Z301 is build, as shown in Fig 4.1, published in AEGATS2016_37 paper (BOROT et al., 2016).

Fig. 5.1 Zodiac Seat Z301 Virtual Prototype published in Aegats publication

Then, the human models are seated by simulation on this seat with a standard and repeatable seating procedure in three different postures:

 TTL (Taxi / Take off / Landing) where the backrest is in its straight position, and the main support is brought to the human by the bottom cushion,

 Reclined where the backrest is reclined and the support of the bottom cushion is diminished,

 Relaxed where the backrest is in its straight position and the occupant bends his spine laterally in order to position one of his arms on the armrest.

Fig. 5.2 Postures used for comfort evaluation in Zodiac Seat Z301

5.3 Pressure Mapping simulation results 5.3.1 Overweight human model

The maximum pressure is reduced under the ischions, leading from a non-comfortable situation (red cells from the Mergl criteria) to a non-comfortable one (green cells from the Mergl criteria) (see Figure 5.3.).

Fig. 5.3 Mergl criterion applied to the two postures of the overweighted individual 5.3.2 Eldery human model

For the elderly person, in the TTL position, the peaks under the ischions have higher values than for the standard person. It may be due to less muscular tonus and/or reduced flesh thickness. The same trends are observed between TTL and reclined postures (see Figure 5.4).

Fig. 5.4 Mergl criterion applied to the three postures of the elderly individual

5.3.3 Disable human model

Fig. 5.5 Mergl criterion applied to the three postures of the disabled human model For the paraplecix human midel, the average pressure is very weak in reclined position, under the discomfort limit; additionnaly to the instability issues.

6 Conclusion

Human models have been developed in order to represent overweight, elderly and paraplegic people. Those models have been used on aircraft seats in order to evaluate discomfort for those populations. Next steps of the project consist in using this simulation capability in order to propose new seat design enabling a better accomodation for all passengers types.

Acknowledgements

Part of this study comes from research work supported financially by Zodiac Seat France and Direction Generale de l'Aviation Civile (project n_2014 930818)

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