Dear everyone,
I have been creating plasticity-damage based concrete model with gradient nonlocal approach. I have already created concrete model and implemented it in ANSYS through the usermat. I'm currently working on the gradient nonlocal approach. I want to implement it through the ANSYS user-defined element (user300). As a first step I’ve created single element model (1*1*1 m cube) . I use following APDL commands in order to create element:
*SET,ELEM_TYPE_ID,102
TYPE,102
ET,ELEM_TYPE_ID,USER300
USRDOF, DEFINE, UX,UY,UZ
USRELEM,20,3,BRICK,0,20,20,1,8,3,0
And
/prep7
EMODIF,ALL,TYPE,ELEM_TYPE_ID
ALLSEL,ALL
/solu
As a result I got this message:
*** ERROR *** Negative element Jacobian value 0 at element 1. This is due to wrong element order or bad mesh.
I didn’t change element code before compiling; tried it in ANSYS 19.2 APDL and Workbench. Obviously, mesh has a perfect quality.
Could you tell me how to solve this problem?
I've solved this problem. For 20 node bricks with 8 integration points this keyopt has to be included:
KEYOPT,ELEM_TYPE_ID,1,1
otherwise, ANSYS uses options for 2D shells
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