# The Largest Couple that Can Be Applied to a Beam in Pure Bending

A beam of cross section shown is extruded from an aluminum alloy for which σy = 310 MPa and σu = 480 MPa. Using a factor of safety 3, determine the largest couple which may be applied to the beam when it is bent about the z axis.

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Given: σy = 310 MPa, σu = 480 MPa, factor of safety = 3

Find: largest couple (M) which may be applied to the beam when it is bent about the z axis.

Solution:

For this problem, we have a beam in pure bending where the neutral axis passes through the centroid of the cross section, so we can use the following formula:

(1)

where ...

#### Solution Summary

The solution determines the largest couple which may be applied to the beam when it is bent.

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