Local Strengthening of Skin : Doubler Design

• Jun 19, 2023

• #2

rb1957

Aerospace

Apr 15, 2005

16,133

CA

you'll probably need more than doublers, depending o the significance of the load. Typically the critical load is out-of-plane (of the antenna) putting torque into the skin. We find that a U-channel typically kills this problem "dead".

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

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• Jun 19, 2023

• #3

SWComposites

Aerospace

Nov 6, 2000

3,717

US

Ah, re "composite skin of an aircraft" - what exact aircraft? where on the aircraft? solid laminate or sandwich panel?

Flabel and Niu don't cover composite structure stress analysis. You are going to need a composites expert to help with this.

 

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• Jun 20, 2023

• Thread starter
• #4

zainulabidin

Aerospace

Jun 19, 2023

2

PK

the skin is composite laminate. There are no stiffener or bulkhead in vicinity of installation area.
are there any references?

 

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• Jun 20, 2023

• #5

SWComposites

Aerospace

Nov 6, 2000

3,717

US

I doubt you will find a reference, except if this is for some sort of kit airplane. Its not a simple design. Would help if you provided a drawing and loads.
Please answer all of the previous questions. Plus,
Is this for a pressurized fuselage?
Is this a one off or serial production?
Who is the certifying agency?

 

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• Jun 20, 2023

• #6

Stress_Eng

Aerospace

Jun 15, 2019

240

GB

Just food for thought. Are you able to determine equivalent axial and bending moduli, in the two perpendicular axes of the skin? Would you then be able to investigate plate displacement behaviour under the combination of existing and new load conditions, taking into account load transfer between the skin and the doublers?

 

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• Jun 20, 2023

• #7

rb1957

Aerospace

Apr 15, 2005

16,133

CA

along with SWC's questions ... how big is this antenna ? (large VHF, small L-band ?)
What is causing these "significant" loads ?
Is the composite it is mounted on laminate or sandwich ?
It sounds like you're introducing a moment into a "plate" and this is going to be harder to reinforce and substantiate.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

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• Jun 20, 2023

• #8

WKTaylor

Well-known member

Sep 24, 2001

4,302

US

In addition to everyone else's questions...

Be explicit... which 'Niu' textbook are You referring-to?

What is the size of the antenna and the 'foot print' [mounting/bolting pattern]?

High radius of curvature? Compound curvature? Is this install on the upper, side or lower surfaces of the fuselage[?] or ????.

How is the 'antenna backplane' and bonding been defined? Have moisture sealing and grounding... for static/corona and lightning... design issues been considered?

Is the composite structure hand-laid-up... or mandrel-wound.... directional fiber/tape, woven cloth, etc?





Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

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• Jun 23, 2023

• #9

WKTaylor

Well-known member

Sep 24, 2001

4,302

US

zainulabidin appears to be taking some time to think about our responses... before replying?

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

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