11. User-supplied Models

This chapter describes the predefined user-supplied subroutines for material models for nonlinear structural analysis.

• The user-supplied subroutines should be coded with great care. The routine should perform the intended function without influencing other parts of DIANA. See Volume Analysis Procedures for the precautionary measures to be taken when applying user-supplied subroutines.

• The user-supplied subroutines should be developed and tested on a single element example to verify if the routine models the intended behavior accurately before using the subroutine in production analyses.

See also Volume Analysis Procedures for a general description of DIANA's user-supplied subroutine option.

Stress and strain vectors.

Many of the user-supplied subroutines have strain or stress vectors in their argument list. The length and contents of these vectors depend on the stress situation, c.q. the element family for which the routine is called. Unless otherwise specified, the contents of the strain and stress vectors are as indicated in Table 11.1.

Table 11.1: STRESS AND STRAIN VECTORS IN USER-SUPPLIED SUBROUTINES

Element family	ns	sig(ns) dsig(ns)	eps(ns) eps0(ns)
Truss elements	1a	$\sigma_{{xx}}^{}$	$\varepsilon_{{xx}}^{}$
	3bc	$\sigma_{{xx}}^{}$,$\sigma_{{yy}}^{}$,$\sigma_{{zz}}^{}$	$\varepsilon_{{xx}}^{}$,$\varepsilon_{{yy}}^{}$,$\varepsilon_{{zz}}^{}$
Two-dimensional class-II & -III beams	2a	$\sigma_{{xx}}^{}$,$\sigma_{{xy}}^{}$	$\varepsilon_{{xx}}^{}$,$\gamma_{{xy}}^{}$
	4bc	$\sigma_{{xx}}^{}$,$\sigma_{{yy}}^{}$,$\sigma_{{zz}}^{}$,$\sigma_{{xy}}^{}$	$\varepsilon_{{xx}}^{}$,$\varepsilon_{{yy}}^{}$,$\varepsilon_{{zz}}^{}$,$\gamma_{{xy}}^{}$
Three-dimensional class-II & -III beams	3a	$\sigma_{{xx}}^{}$,$\sigma_{{xy}}^{}$,$\sigma_{{zx}}^{}$	$\varepsilon_{{xx}}^{}$,$\gamma_{{xy}}^{}$,$\gamma_{{zx}}^{}$
	5bc	$\sigma_{{xx}}^{}$,$\sigma_{{yy}}^{}$,$\sigma_{{zz}}^{}$,$\sigma_{{xy}}^{}$,$\sigma_{{yz}}^{}$	$\varepsilon_{{xx}}^{}$,$\varepsilon_{{yy}}^{}$,$\varepsilon_{{zz}}^{}$,$\gamma_{{xy}}^{}$,$\gamma_{{yz}}^{}$
Plane stress elements	3a	$\sigma_{{xx}}^{}$,$\sigma_{{yy}}^{}$,$\sigma_{{xy}}^{}$	$\varepsilon_{{xx}}^{}$,$\varepsilon_{{yy}}^{}$,$\gamma_{{xy}}^{}$
	4bc	$\sigma_{{xx}}^{}$,$\sigma_{{yy}}^{}$,$\sigma_{{zz}}^{}$,$\sigma_{{xy}}^{}$	$\varepsilon_{{xx}}^{}$,$\varepsilon_{{yy}}^{}$,$\varepsilon_{{zz}}^{}$,$\gamma_{{xy}}^{}$
Plane strain & axisymmetric elements	4ab	$\sigma_{{xx}}^{}$,$\sigma_{{yy}}^{}$,$\sigma_{{zz}}^{}$,$\sigma_{{xy}}^{}$	$\varepsilon_{{xx}}^{}$,$\varepsilon_{{yy}}^{}$,$\varepsilon_{{zz}}^{}$,$\gamma_{{xy}}^{}$
Curved shell elements	6abc	$\sigma_{{xx}}^{}$,$\sigma_{{yy}}^{}$,$\sigma_{{zz}}^{}$ = 0,$\sigma_{{xy}}^{}$,$\sigma_{{yz}}^{}$,$\sigma_{{zx}}^{}$	$\varepsilon_{{xx}}^{}$,$\varepsilon_{{yy}}^{}$,$\varepsilon_{{zz}}^{}$,$\gamma_{{xy}}^{}$,$\gamma_{{yz}}^{}$,$\gamma_{{zx}}^{}$
Solid elements	6abc	$\sigma_{{xx}}^{}$,$\sigma_{{yy}}^{}$,$\sigma_{{zz}}^{}$,$\sigma_{{xy}}^{}$,$\sigma_{{yz}}^{}$,$\sigma_{{zx}}^{}$	$\varepsilon_{{xx}}^{}$,$\varepsilon_{{yy}}^{}$,$\varepsilon_{{zz}}^{}$,$\gamma_{{xy}}^{}$,$\gamma_{{yz}}^{}$,$\gamma_{{zx}}^{}$
Embedded bar reinforcements	1a	$\sigma_{{xx}}^{}$	$\varepsilon_{{xx}}^{}$
Embedded grid reinforcements	2a	$\sigma_{{xx}}^{}$,$\sigma_{{yy}}^{}$	$\varepsilon_{{xx}}^{}$,$\varepsilon_{{yy}}^{}$
	a For subroutines USRMAT, USRLIQ.
	b For subroutines ELSEUS, ELSGUS, USRUNL.
	c For subroutine USRMNL.