Currently, I am simulating a Charpy impact phenomenon on a LS-DYNA platform (ANSYS-APDL). All was right until I tried to divide the specimen into three parts and assign it different properties that would belong to a welded joint (WM, BM and HAZ) but when I do it the following error appears.

Error 20431 (STR+431)

PART ID "": has negative or zero yield stress.

those PART ID's are the ones created when I divide the specimen.

PS1: I've tried meshing them, sweeping them, and I've used the boolean tools glue and divide.

PS2: I've tried the assembly command

PS3: I've tried separating each material with a different type and using different materials with the same type

PS4. This error doesn't appear when simulating the specimen with just one material.