Mechanical Engineering - Strength of Materials - Discussion

Discussion Forum : Strength of Materials - Section 1 (Q.No. 7)
7.
A body is subjected to a tensile stress of 1200 MPa on one plane and another tensile stress of 600 MPa on a plane at right angles to the former. It is also subjected to a shear stress of 400 MPa on the same planes. The maximum normal stress will be
400 MPa
500 MPa
900 MPa
1400 MPa
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
57 comments Page 5 of 6.

Pradeesh said:   1 decade ago
Principal stresses are the stresses in the planes, where shear stress is equal to zero! so the principal stresses are essentially maximum and minimum normal stresses, with an angle of 90 degrees between them!

Sumit said:   1 decade ago
Principal Stress: Maximum and minimum normal stress possible for a specific point on a structural element.

Rahul prajapati said:   1 decade ago
Normal stress and maximum stress difference tell me.

SUJAY LONDHE said:   1 decade ago
Normal Stress = (Shear Stress*sin2theta)+((Fx+Fy)/2)+(((Fx-Fy)/2)cos2theata).

In this Case theta = 90 because they are at right angle.
Other all values are given on calculation we get ans A)400.

Reference: Strength of materials by R.K.Rajput.
Chapter 2, Page NO.95 Eq.2.8.

Rahul prajapati said:   1 decade ago
@Amol and @Arshad this formula is used for max. Principal stress not for max normal stress.

Zaid said:   1 decade ago
Normal stress = (Fx+Fy)/2 + 1/2* ((Fx-Fy)^2 +4(txy)^2)).

Arshad said:   1 decade ago
900+1/2(600*600+4*400*400)^1/2 = 1400.

Khagesh said:   1 decade ago
Principal stress are maximum and minimum normal stress which may be developed on a loaded body.

Khagesh said:   1 decade ago
We can get max normal stress from: x+y=n1+n2.

The formula given above is wrong for max normal stress if you don't believe it solve it.

Mahender Rana said:   1 decade ago
Yes I am agree with @Kaushal that normal and principal stresses are not same, then how it is possible to use same formula.


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