# Anyone have experience with gas turbine blade stress analysis?

1. Feb 5, 2014

### AeroStudent

I'm doing a survey on the topic of "gas turbine blades stress analysis" to see what areas are not focused on in this subject.

I've found that not many people talk about the aerodynamic forces on the blade. Am I missing something, are they included in the calculation or are they too small to consider? Is it worth it to investigate this area?

And does anyone have good resources to study in this area (papers, journals, books,...etc.) , I'm especially interested in the subject of the forces on the blade and how they are distributed.

2. Feb 5, 2014

### AlephZero

For the rotors, compare the centripetal forces on a typical blade with the aerodynamic forces, and the answer should be fairly obvious. Of course there are no centripetal forces of the stators (often called "guide vanes").

3. Feb 5, 2014

### AeroStudent

well that's the thing i couldn't find any paper or source that specifies the aerodynamic forces , i know they are very small compared to other stresses but my question is by how much and is it worth it to look into them.

4. Feb 7, 2014

### AlephZero

It is not just a question of how big the forces are. You also need to consider the change in stiffness of the blade caused by the internal stresses (similar to stretching a guitar string) and the fact that the centripetal forces change as the blade changes shape (because the $r$ in $mr\omega^2$ changes).

If you model a fan blade on a large jet engine as a cantilever beam, and do a linear analysis applying the gas loads as a distributed load along the length of the beam, you will probably get a deflection of the blade tip of the order of 0.5 meters. That is obviously nonsense compared with what happens in real life, and shows how important the nonlinear behavior is.