Dear Dr. Bergstrm
My name is Per Bryntheson and I work at Saab Automobile AB in Trollhttan, Sweden.
I just found the card *HYSTERESIS in the ABAQUS manual and that is exactly what I need. I also found the reference to yours and Boyce report Constitutive Modeling of the Large Strain Time-Dependent Behavior of Elastomers. I have now downloaded all the reports I have found that you have written. I also found your website polymerfem.com. I must say that it felt like winning the lottery when I found all this. The reason to my excitement is that I am working with hood and door slams (fast closings of the car closures) and I therefore need the force displacement curve for the rubber sealings at fast compressions. I do however have some questions that you perhaps would be kind enough to help me with.
I use to calculate the force displacement curve for the sealings in Abaqus/explicit using a plain strain FE-model with displacement driven compression (compressing the seal profile with a rigid body with a friction coefficient of 0.3 between them). I have now tried to implement *HYSTERESIS in my calculation but got into some difficulties. First of all I had to switch to Abaqus/standard since *HYSTERESIS only worked in standard. My big problem is now that the calculation doesnt converge. I have tried to do the calculation in Abaqus/standard without *HYSTERESIS and that works fine, but when I include that card the problem gets really hard to solve for Abaqus.
I am using a mix of CPE3 and CPE4 elements and the rubber material (EPDM 30 shore A) looks like this (my model is in [mm] and I use [N] and [MPa]):
I got the *HYSTERESIS values from the ABAQUS Analysis Users Manual ver 6.5 where they with a reference to you gave the typical values: S=1.6, A=5/((SQRT of 3)^m) = 5/(1.732^4)=0.556, m=4.0 and C=-1.0.
Do you have any ideas on hove I should get convergence? Have I misunderstood the units? should I perhaps try to change any of the *HYSTERESIS values? Should I perhaps make an ever finer element mesh, the elements are already rather small. Do you think that I should try only using triangular mesh (CPE3 elements).
I am grateful to any help from you.
By the way, are you perhaps in any way related to Sweden. It does sound like it on your name Jrgen Bergstrm.