Problems still exist in nanoindentation simulation.

[liuyanjie2020]

Dr.Eralp:
I am still encountering problems when using abq2022 and the latest version UMAT-3.4 for single-phase and multi-phase nanoindentation simulations. Both simulations fail to converge from the first step. I have considered the following:
1. Modification of contact conditions: (1) Add contact stability; (2) Modify the Normal behavior to exponential soft contact; (3) Change finite slip to small slip; (4) Change surface-to-surface contact to General contact;
2. Modify the geometry of the contact surface, from a standard indenter to an indenter with rounded corners, and change the specimen from a cylinder to a plane;
3. Reduce the indentation by a factor of 100;
4. Abandon my custom material parameters and use case (1-3) in usermaterials.f for testing;
5. Global structured mesh;
6. Modify the GND and backstress parameters in the userinput.f file；
However, all of the above attempts have been ineffective. The following are the test inp and experimental：

CPFEM-ping.txt

Meanwhile, the flat indentation example files mentioned above can be found https://github.com/LianjGroup/Abaqus-Nanoindentation-Project/tree/main/templates/PH_ferrite_n20/grain_1441_sr_0p1 (Note: The model was scaled up accordingly for my simulations). For the original .inp file and its matching UMAT, the simulation can run successfully.

  I look forward to having a more in-depth discussion with you @EralpDemir .