Aluminium alloy with an uts of 400MPa and is tested to a ratio of 0.1

[scw1]

Homework Statement

Hi there if you have an aluminium alloy with an uts of 400MPa and is tested to a ratio of 0.1 and the endurance limit is 10^7 cycles is 160MPA what is the mean stress with a stress amplitude of 160MPa, how do i work out the max and min stresses and using the Goodman relation how do i calculate the endurance limit with a mean stress of zero?
SCW1

Homework Equations

sigmam=sigma max+sigma min/2

The Attempt at a Solution

I got 176MPa for mean stress the max stress being 320 and min stess being 32MPa and for the Goodman relation i got 159.9MPa not sure if this is right can anyone help??

 

[KataKoniK]

I would like to offer some guidance and clarification on the calculations you have attempted. Firstly, it is important to note that the given information (UTS, ratio, and endurance limit) is not enough to calculate the mean stress, maximum stress, and minimum stress. These values are dependent on the specific loading conditions and geometry of the material being tested. Therefore, I would recommend consulting with the researcher or engineer who conducted the experiment for more accurate values.

However, if we assume that the uts of 400MPa is the maximum stress and the ratio of 0.1 is the stress amplitude, then we can calculate the mean stress using the equation you have provided: sigmam = (sigma max + sigma min)/2. In this case, the mean stress would be 200MPa.

For the Goodman relation, it is used to calculate the endurance limit of a material under a mean stress. The formula is given as: S'e = Se/(1+sigma m/Sut), where S'e is the endurance limit under mean stress, Se is the endurance limit under zero mean stress, sigma m is the mean stress, and Sut is the ultimate tensile strength. In this case, if we assume a mean stress of zero, the endurance limit would be 10^7 cycles. However, if we use the mean stress calculated earlier (200MPa), the endurance limit would be approximately 10^6 cycles.

It is always important to double check your calculations and assumptions, and to consult with experts in the field for more accurate values. I hope this helps clarify the process and equations for you.