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Silicone Rubber expanding in a closed cavity
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Posted by: Albigger

08/15/2006, 08:10:07

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I'm sorry this is a re-post of an old question (not originally mine) and found here

/engineering-forum/forum.php/?cmd=get&cG=33938363&zu=33393836&v=2&gV=0&p=#3986

but this issue was never really resolved and I'm trying to calculate the same thing.


Closed (cured) silicone rubber in a trapped steel cavity 'mold' and I want to know the resultant pressure inside the cavity as it is heated.

Any help is greatly appreciated. Thank you.

--Jay








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Re: Silicone Rubber expanding in a closed cavity
Re: Silicone Rubber expanding in a closed cavity -- Albigger Post Reply Top of thread Forum
Posted by: Kelly Bramble

08/15/2006, 12:15:33

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The simple answer is that you will need to determine the thermal expansion of both materials. The silicone rubber will likely expand in all directions equally. The cavity material may be more complicated as the material will expand differently depending on material geometry. Keep in mind that the materials may want to "push on one-another" inducing some stress/strain on both materials.

Do you have COSMO's or NASTRAN?







Modified by Kelly Bramble at Tue, Aug 15, 2006, 12:15:59


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Re: Re: Silicone Rubber expanding in a closed cavity
Re: Re: Silicone Rubber expanding in a closed cavity -- Kelly Bramble Post Reply Top of thread Forum
Posted by: Albigger

08/16/2006, 09:12:47

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No, unfortunately no NASTRAN or COSMOS, although we do have Solidworks 2006 which comes with COSMOSXpress module. I have not used it yet though.


It is basically a cylindrical cavity, with constant wall thickness (although the diameter might change along the length). I can calculate the starting cavity volume and predict the heated mold cavity volume. The same with the silicone material (assuming perfect fill), but that still does not seem to help me determine pressure inside the cavity.


I had not considered the deformation of the mold due to the pressure from the silicone, but for a first order approximation I can ignore it (if the resultant pressures are low enough).








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