Mechanical Engineering - Strength of Materials - Discussion

Discussion Forum : Strength of Materials - Section 1 (Q.No. 6)
6.
A steel bar of 5 mm is heated from 15° C to 40° C and it is free to expand. The bar Will induce
no stress
shear stress
tensile stress
compressive stress
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
98 comments Page 7 of 10.

Shubham Gaikwad said:   1 decade ago
Because free expansion of a bar stress will induce in the bar

As =σ = E ε

= E α dt ---- (1).

Where,

σ = Stress due to temperature expansion (N/m2, Pa).
E =Youngs Modulus (N/m2).
ε = Strain.
α = Temperature expansion coefficient (m/m°C).
dt = Temperature differance(°C).

Chetan sagar said:   1 decade ago
Since it is given that condition is Free to expand so no stress is produce because stress is the resistance to the external force.

Udhayaraj said:   1 decade ago
If the bar is free to expand or contract there will be no stress induced in the body.

Mech asar said:   1 decade ago
Steel's melting point is very high so there is no need of worry about stress with out any load apply.

Peter ode eru said:   1 decade ago
Since there is no young modulus in the question, stress cannot be calculated.

Thermal stress = young modulus * stain.
Or
Thermal stress = young modulus*temperature expansion coefficient*temperature difference.

Anush said:   1 decade ago
Stress is depend upon the area.

Mukh Ram meena said:   1 decade ago
The bar free for expansion, so there no stress.

Vikas said:   1 decade ago
@Krish: Thermal stress is dependent on temp because: stress=E*alpha*diff. in temp. wr alpha is co-efficient of thermal expansion.

Krish said:   1 decade ago
Stress is independent on temp but depends on load and pressure(force also).

Vicky said:   1 decade ago
Body itself tends to restrict the expansion, there must be compressive stress induced.


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