Continuum mechanics/Relations between surface and volume integrals
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Surface-volume integral relation 1
[edit | edit source]Let be a body and let be its surface. Let be the normal to the surface. Let be a vector field on and let be a second-order tensor field on . Show that
Proof:
Recall the relation
Integrating over the volume, we have
Since and are constant, we have
From the divergence theorem,
we get
Using the relation
we get
Since and are constant, we have
Therefore,
Since and are arbitrary, we have
Surface-volume integral relation 2
[edit | edit source]Let be a body and let be its surface. Let be the normal to the surface. Let be a vector field on . Show that
Proof:
Recall that
where is any second-order tensor field on . Let us assume that . Then we have
Now,
where is any second-order tensor. Therefore,
Rearranging,