Shear Stress in Dual Core Honeycomb
Shear Stress in Dual Core Honeycomb
(OP)
Hi All,
I can't seem to quite figure out how this works. I'm analysing a honeycomb panel which has a higher density core above a lower density core (for local crushing issues).
When this panel is subjected to bending, is the core shear distributed out depending on the shear modulus and depth of the different cores or is it a usual shear distribution as with using only one core? I can make arguments for both so I'm wondering what the correct answer is and perhaps a source or background reading into why.
To note, there is a single ply between the two core layers to aid manufacturing.
Looking forward to reading your views on this!
Thanks,
Matt
I can't seem to quite figure out how this works. I'm analysing a honeycomb panel which has a higher density core above a lower density core (for local crushing issues).
When this panel is subjected to bending, is the core shear distributed out depending on the shear modulus and depth of the different cores or is it a usual shear distribution as with using only one core? I can make arguments for both so I'm wondering what the correct answer is and perhaps a source or background reading into why.
To note, there is a single ply between the two core layers to aid manufacturing.
Looking forward to reading your views on this!
Thanks,
Matt
RE: Shear Stress in Dual Core Honeycomb
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Shear Stress in Dual Core Honeycomb
But that thinking contradicts that the stiffer material picks up more load...
Are you saying that you would distribute the shear based upon the shear moduli and thickness of the two honeycomb cores?
RE: Shear Stress in Dual Core Honeycomb
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Shear Stress in Dual Core Honeycomb
if you assume both bend (deflect, curve) the same then the stiffer one will react more of the load. but this has each developing bending stress fields, so you'd get an incompatability at the interface.
so what if some of the bending was reacted by a couple between the two core ... the upper one would be in compression and the lower one tension. one idea for the couple is to completely cancel the bending stress,so both have zero stress on the interface. I think this couple may not balance, but I think you can juggle things (what you could call "polishing the tu?d") ...
or you could test it !?
another day in paradise, or is paradise one day closer ?
RE: Shear Stress in Dual Core Honeycomb
Brian
www.espcomposites.com
RE: Shear Stress in Dual Core Honeycomb
can the stiffer core handle the load alone ? or the more continuous core (it sounds like one core might be for local reinforcement).
have you tried an FEA solution ?
another day in paradise, or is paradise one day closer ?
RE: Shear Stress in Dual Core Honeycomb
Yes, ESPcomposites - that is the approach I had taken. I was more asking as a matter of interest as I wasn't sure how to analyse it if, for example, the lower density core was not able to take the entire load.
I may create an FE model to see the result that gives, but I assume that the FE model would split the load according to the stiffnesses.
RE: Shear Stress in Dual Core Honeycomb
Aerospace Stress Analysis and FEA Courses
http://www.stressebook.com
Stressing Stresslessly!
RE: Shear Stress in Dual Core Honeycomb
And last one:
Is this a new design you are working on? Or is it already stress certified and you are trying to do more digging into it by understanding the whole structural behavior?
Spaceship!!
Aerospace Engineer, M.Sc. / Aircraft Stress Engineer
RE: Shear Stress in Dual Core Honeycomb
If I imagine this as a beam in 3 point bending, I would expect the behaviour to be the same as if it were a single core? Tension and compression in the top and bottom faces, with the honeycombs transferring the shear. The denser honeycomb is say 1/3 the depth of the low density honeycomb so the N/A will be within the low density honeycomb. Because of this, I expect the ply in the middle to take some end load as it's not on the N/A... however I planned to assume this was negligible as the ply can't carry much load?
This is already stress certified, I am just trying to understand the whole structural behaviour.
RE: Shear Stress in Dual Core Honeycomb
Once having found your exact location of the N/A in the structure, it would be good to check how it is bonded/fastened to the underlying structure and what kind of structural behavior this other structure would have.
You may have noticed by now- with the location/function/service life parameters, the structural assumptions / exceptions differ a lot. I could exactly guide you through why it has been designed like that accounting for all static/vibrational parameters, but it doesn't look possible to do this from this far and without checking the design and location of the structure. But above might give you some ideas on how to proceed further into your investigation.
It somehow sounds like an automotive design rather than aerospace. But as you posted this in aerospace engineering forum, I'm assuming we are already looking at an aerospace design.
So, my last question would be what kind of aircraft this is on, and where is this panel exactly located at? If it is a helicopter, I'm definitely not that familiar as my primary experience is on commercial aircraft.
Hope I could pinpoint exactly what you were asking. Try to find the stress analysis report for it if you can. Maybe someone in the company retrieved it at some point?
Spaceship!!
Aerospace Engineer, M.Sc. / Aircraft Stress Engineer