Predict failure/defects for the bending of an aluminum profile

Hi, I am trying to simulate the roll bending of an aluminum 6063 profile. I did a static structural simulation with 20 steps of 0.2 seconds, where the profile is supported by two rollers and a third one descends and bends the profile. The purpose of the analysis is to try and find out if this bending radius is possible with this material or not. Im using a bilinear isotropic hardening model for the aluminum. My question is, how would I identify the point of failure or the appearance of defects like thinning or wrinkling or something that could compromise the overall look of the part (its a visible part)? What Im doing right now is first, check that the total strain is not higher than the elongation at break of the material, and second, see the max stress and max strain output of the model and check if its before or after necking occurs, which would be after the material surpasses its ultimate strength (Zone A in the second picture). I thought that if necking occurs, then the material would start thinning or stretching, I dont know if thats the correct interpretation in this case. I would like to know if what Im doing makes sense, or if you have some better ideas of what I should be checking for in the model (or if the model itself could be improved).


Answers

  • @Cocoboat

    You will need a lot smaller elements to accurately capture the plastic strain developing in the model. The mesh you show is way too coarse.

    You will need even smaller elements to capture wrinkling in the model, in addition to seeding the model with a geometric imperfection to initiate the wrinkling.

  • @peteroznewman

    Hi Peter, thank you for your reply. I tried with a smaller mesh (10 mm), would you recommend trying with an even smaller size? I was sort of expecting to see the material stretch or get thinner along the outer bend, is that because my mesh isstill too big?


  • @Cocoboat

    Your part has a thick wide part and a standing rib on one edge. It would be best to have at least 4 elements through the thickness instead of 2, and 8 elements would be even better. The 3 elements on the standing rib could be increased to 4 elements.

    Does the standing rib hang over the edge of the outer rollers?

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