divan arm loads
divan arm loads
(OP)
I'm trying to find which loads do I have to use for a side-facing divan arm stress analysis.
Thank you
Thank you
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RE: divan arm loads
is it placarded "not to be occupied in event of a crash" (i do think that one !) ?
if not, then it'd be the standard crash loads for the divan alone (9g fwd, 3g side).
then there'd be the case when it's occupied in-flight (weight = divan + occupyant(s)) to ult flight inertia up/down
RE: divan arm loads
thank you
Sorry I just subscribe to this site and I didn't find yet how to reply to your post or if this the way to reply.
RE: divan arm loads
I would also look at TSO-C39 and SAE Aerospace Standard AS8049.
As an aside, I worked on a project several years ago for sideways facing seats and saw a video from the Civil Aeromedical Institute. The video showed sled tests of dummies in foward/side and aft facing seats. The human body is not designed to take 9g's in it's side.
RE: divan arm loads
it's your divan, so you can limit it if you want.
if it is occupied for take-off, then the crash cases apply to the divan and it's occupants (185 lbs now). i suspect that allowing some load to be reacted by nearby structure was required becuase the divan alone wasn't able to handle the load.
if it is to be occupied, i'd chat with your airworthiness people, in case they want some special consideration for the side orientation (FAR25.785 doesn't give much insight !).
remember, the up/down loads from from the ultimate flight envelope (the local fuselage acceleration where the divan is placed).
RE: divan arm loads
RE: divan arm loads
That study/video was probably:
DOT/FAA/AM-07/13
Office of Aerospace Medicine
Washington, DC 20591
Assessment of Injury
Potential in Aircraft Side-
Facing Seats Using the ES-2
Anthropomorphic Test Dummy
It is a very interesting read, let me know if you can't find it in the public domain....it will put you off sitting in a sidefaceing seat anyway :)
Regarding Sidefacing seats, my only experience has been in rotorcraft and not typically analysing the seat structure, however I do recall it very imporatant to have the correct type of harness installed, ie a standard 4 point harness is not really suitable, something like a TARC harness is better. I also recall armrests are not that crash-hot for divans - I would definitely agree with rb1957 that the divan should be placarded "not for takeoff/landing".
to the OP, I suspect that report may have some loads in it which may indicate whether your heading in the right direction - its been awhile since I have read it!
RE: divan arm loads
Thank you very much for your help - it's an amazing experience for me to receive so much help from people I don't know, from people having so much knowledge.
RE: divan arm loads
i scanned 25.562, didn't see any reference to "automotive". what about all the other requirements of 562 (beat tension loads, HIC, ...) ?
is it possible to add an airbag to the adjacent unit ? (following on from the "automotive" comment)
RE: divan arm loads
page 38
d. Side-facing Seats.
(1) General. All seats occupiable for takeoff and landing are subject to the
specified dynamic test conditions. Included are side-facing seats and both single
occupancy and multiple place seats, such as divans. Compliance with the structural
requirements should be demonstrated for side-facing seats, using the same conditions for
the test and pass/fail criteria as for fore- and aft-facing seats. The seat should be loaded
in the most critical case structurally. Means of restraining the ATDs may need to be
adapted to ensure adequate retention during the test. The application of floor distortion
will need to be assessed on an individual basis, depending on the design of the fixation of
the seat. The injury criteria of § 25.562 are not adequate to demonstrate equivalent safety
of side-facing seats when compared to fore- and aft-facing seats.
To demonstrate equivalent safety fully in the absence of such specified criteria, the applicant must use other injury criteria which may be derived from the automotive industry, which uses side-impact ATDs.
(2) Assessment criteria. Research into side-facing seats is ongoing. As
research proceeds, the FAA will work toward establishing a more definitive policy with
respect to the acceptance of side-facing seats. Until then, in the absence of specific
compliance guidance, the FAA is prepared to assess side-facing seats on the following
basis:
(a) The seat must demonstrate compliance with the structural requirement.
(b) If an acceptable side impact ATD has not been used with assessment of
the corresponding injury criteria, it must be shown that the occupants are restrained in a
manner that prevents substantial energy absorption by body to body contact (on a
multiple occupancy seat) and which, using the best available engineering judgment,
minimizes injury to the occupant(s).
RE: divan arm loads
Sideways facing is just not a safe idea for takeoff/landing unless there's support for the head. And such support would probably not be aesthetically pleasing. IMHO.
RE: divan arm loads
If 25.562 is part of your cert basis, then the end cabinet will have to be there for test - of the occupant interaction, not its strength (I have never seen a crash pulse accepted totally in lieu of 3 second static). But for the cabinet itself, to show 25.561 compliance you do not have to include the loads an occupant places on it, because in .561 the occupant and cabinet are separate masses. If your cabinet attaches to the divan frame, the the frame needs to be strong enough to take those loads too. So unless the seat belts attach to the cabinet - analyze them separately.
As to some of the, well, ignorance - side facing divans are quite common. And safe. 9g's is next to nothing, 16g's too in comparison to the 30-40g's in a frontal car crash and 60-some g's in a side collision. As a matter of fact automotive side impact dummies are specified for these tests. Unfortunately there is nothing convenient and completely codified yet for 25.562 like AC25.562-1B and AS8049, go to the various exemptions and Equivalent Level of Safety findings. Areas of interest are torso trauma index, occupant-to-occupant contact, and leg loads (though not femur loads; I never saw any that amounted to much). And there are no side facing TSO-C127a products yet, they are to TSO-C39b but have been dynamically tested. Belt geometry is critical, and looks "odd", the lap belt on the leading hip anchors behind the middle of the back.
Divan vendors will help you to a limited extent, but they do not know anything about your particular installation. And one last item, you still need to show compliance to 25.785 so any nearby items would need to be padded.
RE: divan arm loads
Sounds like you have experience in this area. Admittedly, I haven't done much bizjet work.
Thanks for keeping me straight.