Abstract:
Due to the competitive nature of airline industry and the desire to minimise
aircraft weight, there is a continual drive to develop lightweight, reliable and
more comfortable seating solutions, in particular, a new generation slim
economy seat. The key design challenge is to maximise the “living space” for
the passenger, with strict adherence to the ‘Crash Safety Regulations’.
Cranfield University is addressing the needs of airliners, seat manufactures and
safety regulating bodies by designing a completely novel seat structure coined
as “Sleep Seat”. A generous angle of recline (40 degree), movement of “Seat
Pan” along the gradient, fixed outer shell of the backrest, and a unique single
“Forward Beam” design distinguishes “Sleep Seat” form current generation
seats. It is an ultra-lightweight design weighing 8kg (typical seat weight is 11kg).
It has to sustain the static (CS 25.561) and dynamic (CS25.562) “Emergency
landing” loads as specified by “Certification Specifications (CS).
Apart from maintaining structural integrity; a seat-structure must not deform,
which would impede evacuation, should absorb energy so that the loads
transferred to Occupants are within human tolerance limits and should always
maintain survivable space around the Occupant. All these parameters, which
increase a life-expectancy in a ‘survivable’ crash, can be estimated using either
experimental testing or virtual simulation tools such as “Finite Element Analysis
(FEA). Design of the “Sleep Seat” is still in its conceptual phase and therefore
experimental testing for all the design iterations involved is unrealistic, given a
measure of the costs and timescales involved.
Therefore focus of research is to develop practical and robust FE
methodologies to assess static and dynamic performances of a seat-structure
so as to compare different design concepts based on their strength, seat
interface loads (a limit defined by strength of aircraft-floor), maximum
deformations and cross-sectional forces ... [cont.].
