I am working on a 3D Lagrange type 8 node element UELMAT implementation (similar to C3D8 elements). When calling the material_lib_mech routine, as outlined in the manual:

call material_lib_mech(materiallib,stress,ddsdde,stran,dstran,
    kintk,djac,dvmat,xx1,predef_loc,dpredef_loc,npredf,celent,coords_ip)

I always get the error

*** ABAQUS/standard rank 0 encountered a SEGMENTATION FAULT
*** ERROR CATEGORY:  ELEMENT LOOP

if

npt != 1

So, if I call the UELMAT subroutine with simply fixating npt to 1 but doing all other calculations for all integration points, I do not experience any errors (Hence, I only fool the material_lib_mech subroutine on the actual integreation point number). The examples given in the user subroutines manual and verification manual (both are only 2D) run flawlessly.

I checked this with both, Abaqus 2020 and 2022, together with the 2019 Intel Fortran compiler.

Has anyone experienced something similar?

Tanks in advance,
Josef