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FEA Results interpretation for these 3 simulations (stuck on questions)

HI

Im kind of stuck not sure if what i put is ok or correct. Im studying online so not alot of help
As well not 100% on the diagrams

FEA was used to carry out analysis on 3 structures and diagram results obtain (no data), only these 3 pics
(Q) Explain where the first point of failure is likely to originate, and why.
(Q) An analysis of the studies, do you think that they will be an accurate representation of what will happen in practice?



Red indicates high stress and blue indicates low stress

For the (i) there is high stress at both ends and low stress in center. I believe 1st point of failure would be at centre (blue area) and not indicated on diagram of high stress (red). Trusses support the bridge and take the majority of the load and stresses. Blue section centre of the bridge and where load and stress will be most concentrated. contentrated stresses and loading will likely fatigue in beam.

For the (ii) there is high stress at each blade and low stress at the base. I believe 1st point of failure would be at blade (red). Impeller blade are the thinest point on the structure. strength in this area is lowest compared to base. excess high vibration could lead to fatigue and first point of failure.

For the (iii) there is high close to the small end and low stress in big end. I believe 1st point of failure would be at small end (red). connecting rod under goes compression and tension in operation. high speed causing high rpm lead to stretching of the rod leading to failure.

Im not sure if the FEA diagrams are correct or what they are showing. Struggling to find what to compare them with because i dont know what there showing.

I believe (i) is inaccurate but (ii and iii) are accurate. how do i compare accuracy with only pics and no data.



Reply 1
What your stating for question 1 logically seems fine so max stress for an centrifugal impeller usually happens at the blade tip. For a truss usually at the fixed end joints etc…

For question 2 you can’t compare data with just images. You need the data that something like Abaqus would output after running the sim to make that justification. But Q2 I’m sure isn’t asking that you’d need to run an experimental analysis to compare against the numerical analysis they’ve given you
Reply 2
Original post by _Case
What your stating for question 1 logically seems fine so max stress for an centrifugal impeller usually happens at the blade tip. For a truss usually at the fixed end joints etc…

For question 2 you can’t compare data with just images. You need the data that something like Abaqus would output after running the sim to make that justification. But Q2 I’m sure isn’t asking that you’d need to run an experimental analysis to compare against the numerical analysis they’ve given you


Hi

help is limited from tutor online, all they said was compare images with others. no data, simulation tools, info on what these images show or anything was given. I dont know what they are showing the images can you help. I guessed they all showed stress but not sure and cant find image a close enough image for the Truss Bridge.

For the fixed end points at ends of the truss, would there be 1st point of failure instead of middle. i guess becuase compression or fatigue.

cheers

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