5.2.1 Hill

    (syntax)

YIELD

HILL specifies that the Hill criterion must be used [§17.2.1].

YLDOPT

optnam is an option for the yield criterion. MATAXI for yield stresses $\sigma_{{\mathrm{y}}}^{}$ defined in principal anisotropic directions. OFFAXI for yield stresses $\sigma_{{\mathrm{y}}}^{}$ defined with a 45° off-axis tensile test.

YLDSIG

sigy are the yield stresses $\boldsymbol\sigma$_y . The type and number of stresses to be input depends on the option and the element family as outlined in Table 5.1.

Table 5.1: YIELD STRESSES HILL

Option	Element fam.	sigy
MATAXI	pl. stress	$\sigma_{{\mathrm{y} . xx}}^{}$  $\sigma_{{\mathrm{y} . yy}}^{}$  $\sigma_{{\mathrm{y} . zz}}^{}$  $\sigma_{{\mathrm{y} . xy}}^{}$
	pl. strain
	axisymm.
	solid	$\sigma_{{\mathrm{y} . xx}}^{}$  $\sigma_{{\mathrm{y} . yy}}^{}$  $\sigma_{{\mathrm{y} . zz}}^{}$  $\sigma_{{\mathrm{y} . xy}}^{}$  $\sigma_{{\mathrm{y} . yz}}^{}$  $\sigma_{{\mathrm{y} . zx}}^{}$
	shell
OFFAXI	pl. stress	$\sigma_{{\mathrm{y} . xx}}^{}$  $\sigma_{{\mathrm{y} . yy}}^{}$  $\sigma_{{\mathrm{y} . 45\text{\textdegree}}}^{}$  $\sigma_{{\mathrm{y} . xy}}^{}$
	pl. strain
	axisymm.
	solid	$\sigma_{{\mathrm{y} . xx}}^{}$  $\sigma_{{\mathrm{y} . yy}}^{}$  $\sigma_{{\mathrm{y} . 45\text{\textdegree}}}^{}$  $\sigma_{{\mathrm{y} . xy}}^{}$  $\sigma_{{\mathrm{y} . yz}}^{}$  $\sigma_{{\mathrm{y} . zx}}^{}$
	shell

    (file.dat)

'MATERI'
  1   YOUNG    1.0E8
      POISON   0.0
      YIELD    HILL
      YLDOPT   MATAXI
      YLDSIG   1.0E3 1.0E3 1.0E3 0.577E3 0.577E3 0.577E3
'GEOMET'
  1   XAXIS    1.0  0.0  0.0
  2   XAXIS    1.0  0.0  0.0