Epoxy behaviour

[SiggiN]

Hi all!

Suppose you have a cannister with the following cross section:

The cannister is subject to hydrostatic pressue, that will deflect the top plate (assume simply supported) My main concern is excessive deflection of the top plate.

I'm curious how the epoxy will behave over time, given that there is little to no volume for the epoxy to escape to. Are there any effects that will change the volume of the epoxy?

The epoxy layer is 5-10mm thick

As I understand it:

- Epoxy will creep over time, which is basicly a reduction in Elastic Modulus
- The Elastic Modulus is also sensetive to temperature (in my case up to 80degC)

The only paramter I can think of that could change the volume is the poisson's ratio? is this ratio subject to creep/temp. effects?

What will be the consequence if the yield strength is exceeded for enclosed epoxy?

Any thoughts will be appreciated

Regards
Siggi

 

[rickfischer51]

I'm not all that familiar with epoxy. However:

1. Creep is not basically a reduction in elastic modulus. That is a crude idealization so that creep effects can be included in simple hand calculation. Creep is time dependent plastic flow.
2. Epoxy is crosslinked, so its thermoplastic. Creep will me minimal and elastic modulus fairly constant up until it starts to burn.
3. Yield is proportional to the deviatoric stress. Truly hydrostatic pressure results in a dilatational stress which is classically assumed to result in no yielding. Google maximum distortion energy failure theory.
4. Is the epoxy bonded to the top plate, the bottom plate, or both? If the epoxy bonded to both plates, they will act together and deflection will be significantly reduced.


Rick Fischer
Principal Engineer
Argonne National Laboratory

 

[Tmoose]

what is the intended function of the epoxy?
Just to create a seal above the bottom plate? I'm guessing not, but ...............

Do the orange triangles indicate the top plate is simply supported ?

https://www.google.com/url?sa=i&url=http://

http://www.escm.eu.org/eccm16/asset...ved=0CAgQjhxqFwoTCLC8kq2Yh_cCFQAAAAAdAAAAABAP

 

[WKTaylor]

As an aero materials/design engineer this example of using epoxy like this makes no sense.

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
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[Tmoose]

OP's profile says - "My last login was on Wednesday, February 9, 2022."

Looks like after ~ a week without any replies Siggi moved on.