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Elasticity/Sample midterm 1

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Sample Midterm Problem 1

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Given:

The vectors , , and are given, with respect to an orthonormal basis , by

Find:

  • (a) Evaluate .
  • (b) Evaluate . Is a tensor? If not, why not? If yes, what is the order of the tensor?
  • (c) Name and define and .
  • (d) Evaluate .
  • (e) Show that .
  • (f) Rotate the basis by 30 degrees in the counterclockwise direction around to obtain a new basis . Find the components of the vector in the new basis .
  • (g) Find the component of in the new basis .

Solution

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Part (a)

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Part (b)

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Part (c)

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Part (d)

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Part (e)

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Because cannot be an even or odd permutation of .

Part (f)

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The basis transformation rule for vectors is

where

Therefore,

Hence,

Thus,

Part (g)

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The basis transformation rule for second-order tensors is

Therefore,