How to calculate if a part will fail at a specific spot

[ENGBIO]

Hey everybody so I am a student and I am learning about failure analysis. So let's say I have a rigid body that is being kept in this position...there is a moment at A generated by a motor to keep the body in this position, working against the weight of the body itself and small wind force. There are bearing reactions at A. I know about making shear and bending diagrams but when it is angled like this how do I calculate if it will fail at these spots?

 

[FEAnalyst]

Assumption that the part is rigid can't be made in this case when you want to evaluate failure spots. You could solve this as an inclined beam in bending but it won't account for stress concentrations and these will definitely occur in the spots marked with red dots. You would have to perform Finite Element Analysis to calculate von Mises stress at these locations and then compare it with yield stress of the material to find out if failure may occur due to applied load.

 

[ENGBIO]

Assumption that the part is rigid can't be made in this case when you want to evaluate failure spots. You could solve this as an inclined beam in bending but it won't account for stress concentrations and these will definitely occur in the spots marked with red dots. You would have to perform Finite Element Analysis to calculate von Mises stress at these locations and then compare it with yield stress of the material to find out if failure may occur due to applied load.

I think I understand. So if it was instead in this position would it then be possible to calculate if it would fail at those points and how?

 

[FEAnalyst]

The fact that it's at an angle is not a problem. It can be solved as a beam either way. What I meant is that these hand calculations (for both inclined and horizontal beams) can be used to determine overall stress level due to bending in specific cross-section but they can't account for effects occurring around sharp corners. In these locations there are so called stress concetrations (notch effect). Pretty much only FEA with high quality mesh can predict stress state in such cases. I could perform such analysis for you but I need more details about this structure - its size, material, wind force value and so on. And if you have a picture showing how it looks like in real life then it would be very helpful too.