Figure 8.9 shows the strain-stress curve for a given material. What are (a) Young’s modulus and (b) approximate yield strength for this material?
It is clear from the given graph that for stress 150 × 10 6 N / m2, strain is 0.002.
∴ Young’s modulus, Y =\(\frac{ Stress }{Strain }\)
= \(\frac{150 × 10^ 6 }{0.002} \)= 7.5 × 10 10 N / m2
Hence, Young’s modulus for the given material is 7.5 ×10 10 N/m2.
The yield strength of a material is the maximum 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 300 × 106 Nm/2 or 3 × 108 N / m2 .
The stress-strain graphs for materials A and B are shown in Fig. 8.10.
The graphs are drawn to the same scale.
(a) Which of the materials has the greater Young’s modulus?
(b) Which of the two is the stronger material?
Figures 9.20(a) and (b) refer to the steady flow of a (non-viscous) liquid. Which of the two figures is incorrect ? Why ?
The force applied per unit area in mechanics is understood as stress.
σ=FA
The ratio of internal force F that is produced when a substance is deformed, to the area A where force is applied is referred to as stress.
Strain can be referred to as the ratio of the amount of deformation that the body experiences in the direction of force applied to the initial sizes of the body. The relation of deformation in terms of the length of the solid is shown below:
ε=δlL
where,
As strain defines the relative change in shape and it's a dimensionless quantity.
The material's stress-strain curve delineates the connection between stress and strain for materials. In other words, a stress-strain curve is a graphical representation that shows the reaction of a material when a load is applied.