Question

In a Brazilian test, the front view of a homogeneous rock sample is shown in the figure. The failure initiates at the point, where the rock sample is subjected to stress. The failure initiates at the point marked as: 

 

• A. \( M \)
• B. \( N \)
• C. \( O \)
• D. \( P \)

Hint:

In Brazilian tests, failure begins at the point where tensile stress is maximum, which is typically at the center of the disk under diametrical compression.

Answer 1

The Correct Option is C

Step 1: Understanding the Brazilian Test.

In the Brazilian disc test, a disk-shaped rock sample is placed under diametrical compression. This test is used to determine the tensile strength of materials.

Step 2: Analyzing the Stress Distribution.

When the compressive load is applied along the diameter of the disk, it generates a tensile stress at the center of the disk. This tensile stress is maximum at the center, which is point \( O \) in the figure.

Step 3: Understanding Failure Initiation.

Failure typically initiates at the point where the tensile stress is the highest. As the maximum tensile stress occurs at the center of the disk, the failure begins at point \( O \). This is the characteristic behavior observed in Brazilian disc tests.

Conclusion:

The failure initiates at point \( O \), as it is the point where the tensile stress is greatest.