Join the IDNLearn.com community and get your questions answered by experts. Join our interactive community and get comprehensive, reliable answers to all your questions.

Rigid bar ABC is supported by three symmetrically-positioned vertical rods, which are initially unstrained. After load P is applied, the normal strain in rods (2) is 0.0010 mm/mm. Determine the normal strain in rod (1) if there is a gap of 1.0 mm in the connection between rod (1) and the rigid bar at B. Report the strain in mm/mm

Sagot :

Answer:

The answer is below

Explanation:

The lengths of the rods are not given.

Let us assume the length of rod 1 = 1500 mm and the length of rod 2 = 800 mm

Solution:

The normal strain is defined as the change in member length δ divided by the initial member length L. The normal strain (ε) is:

ε = δ / L

δ = εL

For rod 1:

[tex]\delta_2=\epsilon_2 L_2\\\\\delta_2=0.0010\ mm/mm*1500\ mm=1.5\ mm[/tex]

The axial elongation of rod 2 is 1.5 mm. Since rigid bar ABC is attached to rod 2, the rigid bar move down by same amount.

The rigid bar moves down 1.8 mm but rods 1 will not be stretched by this amount. Because there is a gap between rod (1) and the rigid bar at B, the first deflection of 1 mm would not cause an elongation in rod 1. Therefore, the elongation in rods (1) is:

[tex]\delta_1=1.5\ mm-1\ mm=0.5\ mm[/tex]

The normal strain in rod 1 is:

[tex]\epsilon_1=\frac{\delta_1}{L_1} =\frac{0.5\ mm}{800\ mm} \\\\\epsilon_1=0.000625\ mm/mm[/tex]