Hi,
I am an undergraduate student who is working on the final year project to construct a VUMAT for metallic glass and test it using uniaxial compression simulation (dynamic explicit). In order to ensure the input file used to test the VUMAT is working properly, I try to run a simple simulation which does not involving my VUMAT by setting the material properties in input file to be perfectly elastic, with density = 6114 kg/m^3, Young modulus = 2.1E9 and Poisson ratio = 0.3. By these setting I expect the deformation should be homogeneous, which mean my specimen should be deformed evenly in all direction when the piston is moving down. However, the simulation result is deform in an unreasonable way (as shown in picture 1).
When I search for the solution in internet, I read a relevant thread from this forum
[url] https://polymerfem.com/showthread.php...el-input-files [/url]
and found that the input file named case05_ABAx in vumat_nh_inputfiles.zip‎, provided in the thread is actually very similar to my problem, with only differences in specimen dimension (4mm X 4mm X 8mm in my case) and type of test ( tensile test instead of compression test). However, the input file actually able to produce a homogeneous deformation when combining with the VUMAT provided in the thread mentioned above. I try to modify boundary conditions in my input file according to the input file named case05_ABAx but the same problem still occurs. I guess I must messed up the simulation setting again.
Can anyone tell me what is wrong with my input file? Also, I found that the format of input file provided by the link mentioned above is very different with the input file created using ABAQUS CAE, it that called flattened ABAQUS input file? Can anyone tell me more about how and what software is used to create this type of input file and if possible, please suggest some online tutorial or website regarding this topic.
Thanks in advance.
P.S. Similar problem is posted and discuss in [url] http://www.imechanica.org/node/10116 [/url] but havent find the solution yet, hope experts in this forum are willing to give me some opinions
Your figure indicated significant hour-glassing. I recommend that you activate hourglass control (if you havent). Also check the bulk modulus of your material model.
You can create flat Abaqus inp-files from CAE, but most people prefer inp-files made from parts/instances.
-Jorgen