Consider a cylindrical specimen of some hypothetical metal alloy that has a diameter of 10.0 mm. A tensile force of 1500 N produces an elastic reduction in diameter of 6.7 × 10–4 mm. Compute the elastic modulus of this alloy, given that Poisson’s ratio is 0.35. Express the answer in GPa to three significant figures. Answer:

Respuesta :

Answer:

The elastic modulus is 99.7 GPa

Solution:

As per the question:

Diameter of the metal alloy, D = 10.0 mm = 0.01 m

Tensile force, F = 1500 N

Elastic reduction in the diameter of the metal alloy, [tex]\Delat D = 6.7\times 10^{- 4} mm = 6.7\times 10^{- 7} m[/tex]

Poisson's ratio, [tex]\mu = 0.35[/tex]

Now,

Lateral strain is given by:

[tex]\varepsilon_{D} = \frac{\Delta D}{D} = \frac{6.7\times 10^{- 4}}{10} = 6.7\times 10^{- 5}[/tex]

Longitudinal strain, [tex]\varepsilon_{l}[/tex]:

[tex]\varepsilon_{l} = \frac{\varepsilon_{D}}{\mu} = \frac{6.7\times 10^{- 5}}{0.35} = 1.914\times 10^{- 4}[/tex]

Now, stress is given by:

[tex]\sigma = \frac{F}{Area,\ A}[/tex]

where

[tex]A = \pi (\frac{d}{2})^{2} = \pi (\frac{0.01}{2})^{2} = 7.854\times 10^{- 5} m^{2}[/tex]

Now,

[tex]\sigma = \frac{1500}{7.854\times 10^{- 5}} = 19.098\times 10^{6} = 19.098 MPa[/tex]

Now, the elastic modulus is given by:

[tex]E = \frac{\sigma}{\varepsilon_{l}}[/tex]

[tex]E = \frac{19.098\times 10^{6}}{1.914\times 10^{- 4}} = 99.784\times 10^{9}Pa = 99.7 GPa[/tex]