Direction: In a multi-pass operation, a round bar of 10 mm diameter and 100 mm length is reduced in crosssection by drawing it successively through a series of seven dies of decreasing exit diameter. During each of these drawing operations, the reduction in crosssection area is 35%. The yield strength of the material is 200 MPa. Ignore strain hardening.
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The total true strain applied and the final length (in mm), respectively are
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- 2.45 and 817
- 2.45 and 345
- 3.02 and 2043
- 3.02 and 33
Correct Option: C
Di = 10 mm li = 100 mm n = 7
| True Strain ∈ = ln |  | di |  | ² | ||
| df |
| Af = (0.67)7 × | (10)² | 4 |
df = 2.21 mm
| ∈ = 2 ln | | 10 | | ² | ||
| 2.21 |
∈ = 3.02
Constancy of volume
| di²li = | df²lf | 4 | 4 |
lf = 2047.46 mm
