Bending of Beams

In relation to the Neutral Axis of a beam, which of the following are correct (there is more than one correct answer) ?

• Its the center of gravity of the cross sectional area

• Its the plane where stiffness is zero

• Its the plane where zero deflection occurs

• Its the plane where zero deflection occurs

• Its the plane where zero stress occurs

It is possible to remove material located on the edges of an I-Beam (away from the N.A.) without affecting the Stiffness and Strength of the Beam ?

• Yes it is

• No it is not

A beam with a rectangular cross section measures 150mm wide by 200mm high. What is its second moment of area. (Only one correct answer) ?

• 1x10^-4 m⁴

• 100x10⁶ m⁴

• 5.625x10^-8 m⁴

• 4x10^-5 m⁴

How does a strain gauge measure strain ?

• Who knows ?

• It expands and contracts with temperature and thus measures strain

• The stress is measured via a change in force and then converted into strain

• It converts a minute change in resistance into a change in length hence strain

Mark in the Neutral Axis of this Beam