What is the reason why single axis stretching can run, but not cycling?

[kight55]

Hello everyone!
I have created an RVE with notches. By merging the unimportant 3 faces under Fasets in the simulation. msh file into 1 face, it can perform monotonic stretching but cannot run loops. What is the reason for this?

neper -T -n 60 -morpho voronoi -domain "cube(0.288,0.014,0.216)" -transform "cut(cylinder(0.144,0,0.216,0,0.014,0,0.048))" -reg 1
neper -M simulation.tess -order 2
$ fepx
==========================     F   E   P   X   ==========================
Info   : A finite element software package for  polycrystal plasticity.
Info   : Version 1.3.1-1
Info   : Running on 1 cores.
Info   : <https://fepx.info>
Info   : Copyright (C) 1996-2021, DPLab, ACME Lab.
Info   : ---------------------------------------------------------------
Info   : Start time: 2023-9-7 at 8:43
Info   : Loading simulation...
Info   :   [i] Parsing file `simulation.config'...
Info   :   - Material parameters:
Info   :     > Number of phases: 1
Info   :     > phase 1 - crystal type:   FCC
Info   :     > m:               0.500000E-01
Info   :     > gammadot_0:      0.100000E+01
Info   :     > h_0:             0.200000E+03
Info   :     > g_0:             0.210000E+03
Info   :     > g_s0:            0.330000E+03
Info   :     > n:               0.100000E+01
Info   :     > c11:             0.245000E+06
Info   :     > c12:             0.155000E+06
Info   :     > c44:             0.625000E+05
Info   :   - Boundary conditions:
Info   :     > Uniaxial grip
Info   :     > Strain targeting, constant strain rate
Info   :     > Strain rate:   0.100000E-01
Info   :     > Loading direction: x
Info   :     > Loading face: x1
Info   :   - Deformation history:
Info   :     > Number of strain steps: 22
Info   :   [i] Parsed file `simulation.config'.
Info   :   [i] Parsing file `simulation.msh'...
Info   :   - Mesh parameters:
Info   :     > Node number: 11659
Info   :     > Elt  number: 6414
Info   :   [i] Parsed file `simulation.msh'.
Info   : Initializing simulation...
Info   :   - Initializing parallel gather/scatter routines...
Info   :   - Initializing fields from isotropic viscoplastic solution
Info   :     > ITMETHOD_VP: Iteration 1
Info   :       . Solving NL iteration... R = 0.1852E+00 (2185 iters)
Info   :     > ITMETHOD_VP: Iteration 2
Info   :       . Solving NL iteration... R = 0.1905E-01 (2290 iters)
Info   :     > Converged in 2 iterations
Info   :     > Ready for anisotropic elasto-viscoplastic simulation.
Info   : Running step 1...
Info   :   - Increment 1: t = 1.0000 secs, dt = 1.0000 secs
Info   :     > ITMETHOD_EVPS: Iteration 1
Info   :       . Solving SA iteration... R = 0.1641E+00 (3168 iters)
Info   :     > ITMETHOD_EVPS: Iteration 2
Info   :       . Solving SA iteration... R = 0.5298E-01 (3455 iters)
Info   :     > ITMETHOD_EVPS: Iteration 3
Info   :       . Solving SA iteration... R = 0.3428E-01 (3546 iters)
Info   :     > ITMETHOD_EVPS: Iteration 4
Info   :       . Solving SA iteration... R = 0.2904E-01 (3529 iters)
Info   :     > ITMETHOD_EVPS: Iteration 5
Info   :       . Solving SA iteration... R = 0.2684E-01 (3445 iters)
Info   :     > ITMETHOD_EVPS: Iteration 6
Info   :       . Solving SA iteration... R = 0.2591E-01 (3462 iters)
Info   :     > ITMETHOD_EVPS: Iteration 7
Info   :       . Solving SA iteration... R = 0.2565E-01 (3446 iters)
Info   :     > ITMETHOD_EVPS: Iteration 8
Info   :       . Solving SA iteration... R = 0.2582E-01 (3428 iters)
Info   :     > ITMETHOD_EVPS: Iteration 9
Info   :       . Solving SA iteration... R = 0.2635E-01 (3393 iters)
Info   :     > ITMETHOD_EVPS: Iteration 10
Info   :       . Solving SA iteration... R = 0.2719E-01 (3382 iters)
Info   :     > ITMETHOD_EVPS: Iteration 11
Info   :       . Solving SA iteration... R = 0.2827E-01 (3379 iters)
Info   :     > ITMETHOD_EVPS: Iteration 12
Info   :       . Solving SA iteration... R = 0.2949E-01 (3358 iters)
Warning:     > Iterations are diverging.
Error  :     > Failure to converge.
========================================================================

simulation.config.txt
simulation.msh.txt

[rquey]

I think it has already been discussed elsewhere, but FEPX was developed to solve real, 3D problems and will most often fail when run on pseudo-3D problems like this one.

So, it is not really a problem of notch or monotonic vs cyclic loading.