This tutorial introduces the USDFLD subroutine in Abaqus and explains how it can be used to assign material properties based on user-defined field variables. Unlike UMAT, which is intended for defining full material behavior, USDFLD is simpler and better suited for modifying material properties conditionally—based on things like stress, strain, or time. The video clarifies common misunderstandings about these subroutines and highlights where USDFLD is more appropriate. You’ll gain a clear understanding of how to implement USDFLD effectively, and the accompanying PowerPoint offers a concise overview to support your learning.