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Section modulus ratios

engineer121394

Mechanical
Sep 8, 2022
16
My understanding about section modulus ratios:
-given a dimensional deviation or surface flaw on a structure, a section modulus ratio can be used to scale linearized stresses at a cutline (stress classification line) on an FEA model rather than re-running the model.
-area ratios can scan primary membrane stresses
-area second moment ratios can scale primary bending stresses.

My questions:
-is my understanding generally correct?
-What are limitations of using this method? I.e. when is it acceptable/unacceptable to use?
Some drawbacks that I can think of are that it probably doesn’t account for peak stresses and should not be used in areas with local structural discontinuities.
-Does this method work for Secondary stresses as well. I cannot imagine why it wouldn’t.
 
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Where are you getting this from? Is there a reference to this "understanding"?
 

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