Mechanical Engineering - Machine Design - Discussion

If shaft made with the ductile material then they only follow Rankine Theory because it gives a satisfactory result for the shaft. As all knows guys Rankine theory also known as Maximum principal stress theory, therefore, option A is right here.

Thanks.

The principle stress theory is for brittle material.

The principle shear stress theory is specifically for a ductile material.

So, the correct option is B.

Most efficient criteria for ductile material is von mises.

B is the correct answer.

The correct answer is option B.

Maximum shear stress theory is the right one.

In question, there are two points that need to be noted.

1. Ductile. 2. Most conservative.

Hence for ductile with the most conservative maximum principal stress theory is to be considered.

B is the correct answer.

Option D is the right answer, maximum distortion energy theory is applicable.

Actually.
All Theories are Failure material. (Ductile/Brittle)

So
Maximum Principal stress theory Failure Brittle Material.
and Maximum shear stress Theory Failure Ductile Material.

Then;
Noted the Point;
1. Ductile Material.
2. Will Give the Most Conservative Value.

Ductile materials are no Failure which Theory (Conservative Ductile Material)

Maximum Principal Stress Theory is Ductile material Most Conservative (No failure).
Brittle Material Failure (Non-Conservative).

That's why the answer is Option ( A).