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CONTINUUM MECHANICS for ENGINEERS

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Additionally, it is easy to show from Eq 2.2-13 that<br />

and<br />

There<strong>for</strong>e, now Eq 2.2-12 becomes<br />

which may be transcribed into the <strong>for</strong>m<br />

a well-known identity from vector algebra.<br />

(f) tensor product of two vectors (dyad):<br />

which in expanded <strong>for</strong>m, summing first on i, yields<br />

and then summing on j<br />

ε ε = 2δ<br />

jkq mkq jm<br />

ε ε = 6<br />

jkq jkq<br />

( )<br />

u× ( v× w)= δ δ −δ<br />

δ uvw eˆ<br />

mj ik mk ij i j k m<br />

( ) = −<br />

= uv w −uvw<br />

eˆ uwv eˆ uvw eˆ<br />

i m i i i m m i i m m i i m m<br />

u× ( v× w)= ( u⋅w) v−( u⋅v) w<br />

uv= ueˆ v eˆ = uv ee ˆ ˆ<br />

i i j j i j i j<br />

uvee ˆˆ= uvee ˆˆ+ uvee ˆˆ+ uvee<br />

ˆˆ<br />

i j i j 1 j 1 j 2 j 2 j 3 j 3 j<br />

uvee ˆˆ = uvee ˆˆ + uvee ˆˆ + uvee<br />

ˆˆ<br />

i j i j<br />

1 1 1 1 1 2 1 2 1 3 1 3<br />

+ uvee ˆˆ+ uvee ˆˆ + uvee<br />

ˆˆ<br />

2 1 2 1 2 2 2 2 2 3 2 3<br />

+ uvee ˆˆ+ uvee ˆˆ + uvee<br />

ˆˆ<br />

3 1 3 1 3 2 3 2 3 3 3 3<br />

(2.2-14)<br />

(2.2-15)<br />

(2.2-16)<br />

This nine-term sum is called the nonion <strong>for</strong>m of the dyad, uv. An alternative<br />

notation frequently used <strong>for</strong> the dyad product is<br />

u⊗v= ueˆ⊗ v eˆ = uv eˆ ⊗eˆ<br />

i i j j i j i j<br />

(2.2-17)

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