A 12 mm x 12 mm square metal alloy having a gage length of 5

A 12 mm x 12 mm square metal alloy having a gage length of 50 mm was tested in tension. The entire stressstrain curve for the material is shown below on the left. On the right is the enlarged graph of region before point A.

Showing your points and construction on graphs and the associated calculations, determine the following quantities

(a) Ultimate Stress.
(b) Fracture Stress.
(c) Modulus of Elasticity.
(d) Proportional Limit.
(e)Yield stress at 0.2% offset.
(f)Secant modulus at stress level of 1400MPa.
(g) Plastic strain at stress level of 1400MPa.
(h) The extension of the specimen when the axial force on the specimen is 90 kN.
(i) If the material has a Poisson’s ratio of 0.4, what is the change in length of one of the sides of the cross-section at a stress level of 1400MPa.

1600 1200 400 1000 1200 800 1000 600 800 600 400 200 0.00 0.05 0.10 0.15 0.20 0.000 0.002 0.004 0.006 0.008 0.010 0.01 Strain Strain

Solution

ultimate stress is the maximum stress point in the graph ( approx. 1483.33 MPa)

Fracture stress is the point where material cracks ( approx. 1300 MPa )

Modulus of elasticity is a slope of stess strain curve (i.e. E= stress/strain = 600/0.002 = 300 GPa )

Proportinal limit = 1000 MPa