3D beam - interpreting bending results 1

[Kat1990]

Hi all,

My problem at the moment is interpreting results in Abaqus FEA. I have successfully completed my 3D beam test rig and need to find where it is failing through plastic deformation so that I can edit the width of the hollow box beam sections in the model. I am quite new to this and I am trying to get better!

- My hand calculation of stress shows that the model cannot take more than 3000 Pa.
- The material is mild steel: 210e9 (E) and 0.3 (poissons) and density of 7850

1) how do you find yield strength from the results?
2) does the stress from the results have to be above or below the yield strength?
3) how do you interpret von mises?

 

[Dave442]

Hi Kat1990,

1) You don't generally use FEA results to find the yield strength (stress) of a material. If you want to model plastic deformation you have to specify the yield stress prior to carrying out the analysis.

2) If plastic deformation is not desirable in your assembly you should design your rig so that the stresses predicted in the material are lower than the specified yeild stress by some factor of safety.

3) The von Mises stress is an equivalent stress measure that allows the stress state predicted in a material that is subjected to multi-axial loading to be compared against its uniaxial stress-strain response.

Good luck,
Dave