Mechanical Engineering - Strength of Materials - Discussion

Discussion Forum : Strength of Materials - Section 1 (Q.No. 42)
The rectangular beam 'A' has length l, width b and depth d. Another beam 'B' has the same length and depth but width is double that of 'A'. The elastic strength of beam 'B' will be __________ as compared to beam A.
four times
six times
Answer: Option
No answer description is available. Let's discuss.
9 comments Page 1 of 1.

Saiteja said:   3 months ago
E=stress/strains, stress = F/A.
As in the problem said length and depth are the same but worth is different.
E1 = F/b1 * d1,
E2 = F/b2 * d2,d1 = d2,
E1/E2 = 1/2.

Jehan said:   6 years ago
Strength is directly proportional to depth sq x width hence if depth is const. Width will vary. Thus exist linear rship.

Y K Sinha said:   6 years ago
Yes. The answer should be half.

Saif said:   7 years ago
Yes, Agree @Madhu.

The answer should be half.

Nagar said:   7 years ago
A yield strength or yield point is the material property defined as the stress at which a material begins to deform plastically. Prior to the yield point, the material will deform elastically and will return to its original shape when the applied stress is removed.

Madhu said:   7 years ago
My = S * σy.
S = I / y.

So, I think the answer will be half.

Siddu said:   8 years ago
Plese, give a clear solution.

SAURABH said:   8 years ago
Elastic strength directly measure by the term of section modulus.

Than section modulus Z(A) = I(a)/y(a).

Z(A) = (BD^3/12)/(D/2).

= BD^2/6 ------------ equation (1).

Where B is breath and D is depth of rectangular section (A).

According to question B(a) = 2*B(b) in case of Rectangular Section.

Z(B) = (2B*D^3/12)/(D/2).

= BD^2/3.

Then, Z(A)/Z(B) = (BD^2/6)/(BD^2/3).

Z(A)/Z(B) = 1/2.

Z(B) = 2 Z(A).

Manish said:   9 years ago
Elastic strength is directly proportional to section modulus. Z(B) = 2 Z(A)..

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