Question

Figure 9.11 shows the strain-stress curve for a given material. What are
(a) Young’s modulus and
(b) approximate yield strength for this material? Question 9.2 machenical properties of solid

Answer 1

It is clear from the given graph that for stress 150 x 10^6 N/m² , strain is 0.002.

Therefore young's modulus =stress/strain

150 x 10^6/0.002
= 7.5×10^10 N/m²

Hence, Young's modulus for the given material is 7.5 x10^10 N/m²
The yield strength of a material is the maximum m stress that the material can sustain
without crossing the elastic limit.
It is clear from the given graph that the approximate yield strength of this material is 300x10^6N/m²

Answer 2

(a)
Concept :- The slope of straight line portion of strain-stress curve for a given material represent its Young's modulus .
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Young's modulus of the given material = slope of stress- strain graph
= 300 × 10^6/0.004
= 75 × 10^9 N/m²
= 7.5 × 10^10 N/m²

(b)
concept :- Any material can sustain maximum stress is called it's Yield strength .
_____________________________

Yield strength for his material = maximum stress the material can sustain
= 300 × 10^6 N/m²
= 3 × 10^8 N/m²