When calculating the max shear and bending stress in a beam using Sigma b = My/I and Tau = VQ/It, will the calculated stress be accurate past the yield stress for say a ductile steel or since the stress is distributed across more elements as it yields will the elements over yield experience less than the calculated stress. I am trying to compare hand calcs vs FEA. The part I am designing is able to exceed yield and still function safely. Thanks for the help!
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Bending/Shear Stress Elastic vs Plastic Deformation
- Thread starter njm789
- Start date
I am curious how any rigid part could still fulfill its job after surpassing the yield point. I know surpassing yield doesn't automatically mean immediate fracture, but it does mean the part can no longer safely withstand any load. Just curious.
- Thread starter
- #4
HTURKAK
Structural
- Jul 22, 2017
- 3,332
The answer is YES.. the stresses at any point can not be higher than ULTIMATE TENSILE STRENGTH. The Euler- Bernoulli beam theory ( small deflection, plane sections remain plane, and linear distribution of stress ) specially linear distribution of stress is valid up to yield strength is reached.
The following picture depicts the stress strain distribution for elastic , partial plastic and full plastic states.
Notice the similarity of typical stress -strain curve of a ductile material and stress distribution of a bending element.
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