Ultimate Failure of Specimen

[njm789]

Hi,

I have a design where a can is welded inside of a tube. Failure of the device would entail the can separating from the tube. If you were looking to predict or have some criteria to denote this type of failure what would it be eg. any elements that reach the ultimate tensile strength of the material...or the majority of the cross section in a plastic state? Thank you for the help!

 

[FEA way]

If it's welded and you consider failure of the structure when the connection fails and parts separate then you should follow standard weld assessment procedures. Most likely you will have to check this model for fatigue failure apart from static strength evaluation.

 

[njm789]

Thanks for the reply FEA way! This is a one time use device that is exposed to a large force and then disposed of, so fatigue wont be an issue. If the joint was not welded but the part say machined as a single component...how would you ball park separation of material? I have attached a nonlinear FEA of the part. All of the material in the back part has plastically deformed and I would think the curved part of the can would have buckled.

 

[FEA way]

Is geometric nonlinearity included in this analysis ? What is the level of plastic strain ? Some FEA programs (not SW Simulation unforutnately) allow you to define damage initiation and evolution criteria and then remove failed elements from mesh. But in this case you have to take a close look at stresses, strains and deformed shape of the model to judge whether it failed or not.