Vickers hardness: Distance between indentations

Submitted by salveamigos123 on

Hello,
I'm writing here because I don't know how to solve this question that appeared on an exam (undergraduate, mechanical engineering).

The Vickers hardness test was done on a steel plate twice, once with a smaller force and once with a larger force. The first average length of the diagonal is d=0.181 mm. The second indent (larger force was used this time) left the average length of the diagonal d=0.572 mm. What is the minimum distance between indentations?

Hoops stress

Submitted by Audu King Josy on

A steel ring of outer diameter 300mm and internal diameter of 200mm is shrunked unto a solid steel shaft , the interference is arranged such that the radial pressure between the meeting surfaces will not fall bellow 300MN/m^2 while the assembly rotates in circles. If the maximum circumferencial stress on the inside of d surface of the ring is limited to 240MN/m^2. Determine the maximum speed at which the assembly can be rotated . Assuming that no relative slip occur between the shaft and the ring.

Solution to Problem 830

Submitted by griflyn on

I'm learning how to do reactions with the Three Moment Theorem and in the solution for problem 830, it has 1077.27/12 = 538.64.....this clearly isn't correct.

Am I missing something? I tried searching to see if this has been addressed elsewhere, but some guidance would be very helpful and many thanks in advance.