Need help analyzing the failure of a rotating disk

[rafi1800]

Homework Statement

hi,
i'm working on a project for a materials class. we chose to analyze a spacer in a jet engine that catastrophically failed. The spacer failed initially due to rubbing between it and a vane case on the outer most radius of the spacer. We're not analyzing the vane case, so we are focusing on just the spacer. We know that after a lot of rubbing the spacer eventually wore down a bit. After a critical amount of rubbing a crack must have formed somewhere on the rim of the spacer and propagated inward to the smallest radius. At this point the section between the cracks detached. This is how the spacer failed leading to engine failure.

Our problem is that we need to prove this. For simplicity we're only analyzing the spacer as if it failed due to over rotation. We don't have any mathematical support for this...

i found this power point http://www.utm.edu/departments/engin/lemaster/Machine%20Design/Lecture%2016.pdf on another post in this forum

Homework Equations

need them...

The Attempt at a Solution

find $$\sigma_{r}$$ and $$\sigma_{\Theta}$$ max ... but i can't even begin to explain to my prof where these equations came from

 

[Valkarie]

. Is there a material/text book/paper that he can look at to see where i got these equations from? Thank you for your help

 

[Mene]

it is important to approach any problem or analysis with a systematic and logical approach. In this case, the failure of the rotating disk can be analyzed using the principles of mechanics and materials science. First, it is important to understand the loading conditions that the spacer was subjected to, such as the rotational speed, the applied forces, and the contact forces between the spacer and the vane case. This information can be obtained from the engine specifications or through experimental testing.

Next, the mechanical properties of the spacer material should be determined. This includes its strength, ductility, and fatigue resistance. This information can be obtained from material testing or from literature sources.

Once the loading conditions and material properties are known, the failure of the spacer can be analyzed using mathematical equations and principles such as stress analysis, fracture mechanics, and fatigue analysis. These equations can help determine the stresses and strains experienced by the spacer and whether they were sufficient to cause failure.

It is also important to consider any potential defects or imperfections in the spacer that may have contributed to its failure. This can be done through non-destructive testing techniques or by examining the failed spacer itself.

In conclusion, the failure of the rotating disk can be analyzed by considering the loading conditions, material properties, and using appropriate mathematical equations and principles. It is important to gather all relevant information and data in order to provide a thorough and scientifically supported analysis of the failure.