Hello everyone! Im trying to model the mechanical behaviour of a battery cell, considering all of its components (separators, active materials on collectors ecc.). The layer are extremely thin as you can check in the model; i used solid elements with ELFORM=1 for all the parts; i used CRUSHABLE FOAM MATERIAL to model separators and active materials coating the collectors, MAT PLASTIC KINEMATICS to model the aluminum and copper collectors. Furthermore i used the ADD_EROSION to consider the failure of the separators (when a certain number of elements of the separators reach a certain value of strain the simulation terminates). I used ERODING SURFACE TO SURFACE for the contacts among separators and the parts close to them, while i used AUTOMATIC SURFACE TO SURFACE to model the contact between the parts without erosion; in both case i used SOFT=2 SNLOG=1. In control cards i set ERODE=1, ESOERT=3. Now ill explain my problem: as you can see in the picture it seems that some hourglass modes starts at a certain time (i used Hourglass 6 and QH=0.1) but when i check the hourglass energy in GLSTAT i've got that it is a lot smaller than internal energy so i dont understand why this happens! Another Strange thing is related to the fact that the energy ratio is different from 1 as you can see in the picture. What can be the problem? Thank you a lot in advance and greetings from italy!
Ill leave here some pics to understand better the problem
I’m so sorry this was not answered earlier. You may have solved your problem by now (which I’d like to hear how you did) but I would suggest trying to change those part ELFORM to -2. This is a fully integrated formulation that will eliminate the need for defining hourglass control. I’m curious how it would work for this application.
Oh, and I HATE hourglass control in Dyna. That is all.