# Need help analyzing the failure of a rotating disk

1. Oct 19, 2009

### rafi1800

1. The problem statement, all variables and given/known data

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 dont have any mathematical support for this...

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

2. Relevant equations

need them...

3. The attempt at a solution

find $$\sigma_{r}$$ and $$\sigma_{\Theta}$$ max ... but i cant even begin to explain to my prof where these equations came from
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

Last edited by a moderator: May 4, 2017