This chapter discusses additional user programs that can be run with Abaqus. It provides an overview of the following enhancements:

• “VEXTERNALDB: User subroutine that gives control to the user at key moments of the analysis,” Section 13.1

• “VUCHARLENGTH: User subroutine to define the characteristic element length at a material point,” Section 13.2

• “Enhancements to user subroutine UMAT,” Section 13.3

• “Allocatable arrays,” Section 13.4

• “Parallel user subroutines,” Section 13.5