Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
Mises or First-Principle-Stress for laminates?
Posted May 5, 2013, 11:16 a.m. EDT 1 Reply
Please login with a confirmed email address before reporting spam
Hi, someone told me that i should use the First-Principle-Stress- value für a laminate containing glass, polymers and silicon. The setting is: Glass - Polymer - Silicon - Polymer - Polymer 2-BEAM with a fixed constraint and symmetric constraint at the middle. For brittle materials i know ishould use the FPS but it doesnt lead me to a conclusion of my testing results where the Mises value is more constructive.
My question is: When i change the values from Mises to FPS, there are no stresspeaks close to the restraint anymore. In my real case, i got most defects close to the restraint thats why its kind of confusing to have a value of zero MPa at this point. Usually you have stresses at the restraints.
Well i use to have materials that arent brittle in this case too (polymers) even i like to know the stresses at the silicon.
Thanks for the advice. I know im asking many questions but i really need someone to talk to in these things ;)
With special greetings
My question is: When i change the values from Mises to FPS, there are no stresspeaks close to the restraint anymore. In my real case, i got most defects close to the restraint thats why its kind of confusing to have a value of zero MPa at this point. Usually you have stresses at the restraints.
Well i use to have materials that arent brittle in this case too (polymers) even i like to know the stresses at the silicon.
Thanks for the advice. I know im asking many questions but i really need someone to talk to in these things ;)
With special greetings
1 Reply Last Post May 6, 2013, 3:44 a.m. EDT
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi,
Laminates tend to have many different failure modes, which cannot be captured by simple criteria like von Mises or 1st Principal Stress. You need a criterion handling the anisotropy and different failure modes. An example of such a criterion is the Tsai-Wu criterion.
There is no built-in such criterion in COMSOL, but you can easily build your own variable for doing such an evaluation.
Regards,
Henrik
Laminates tend to have many different failure modes, which cannot be captured by simple criteria like von Mises or 1st Principal Stress. You need a criterion handling the anisotropy and different failure modes. An example of such a criterion is the Tsai-Wu criterion.
There is no built-in such criterion in COMSOL, but you can easily build your own variable for doing such an evaluation.
Regards,
Henrik