Join Date: Dec 2008
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It's a composite of two metal skins constrained over a viscoelastic polymer layer. .......or
The invention concerns constrained layer sound damping. A composition and a laminated structure are provided for the reduction of noise coming from housings such as oil pans for automobiles. The composition comprises a rubbery polyurethane, an olefin polymer, and a filler. The laminated structure comprises the housing, the composition, and a sheet metal liner. The composition contains a blowing agent which is activated to provide a single unitary structure which dampens noise. The polyurethane and olefin polymer are thoroughly intermixed with each other, but maintain their separate identities in the blend.
Something like metal walls with substrate to cancel the sound. Heck, you could cast a pan and just flash coat it with something. ....I guess?