**AVPRIN****AVPRIN**, `KEY`

, `EFFNU`

**Specifies how principal and vector sums are to be calculated.**

`KEY`

Averaging key:

**0**
| — | Average the component values from the
elements at a common node, then calculate the principal or vector
sum from the averaged components (default). |

**1**
| — | Calculate the principal or vector sum
values on a per element basis, then average these values from the
elements at a common node. |

`EFFNU`

Effective Poisson's ratio used for computing the von
Mises equivalent strain (EQV). This command option is intended for
use with line elements or in load case operations (**LCOPER**) only; ANSYS automatically selects the most appropriate effective
Poisson's ratio, as discussed below.

### Command Default

Average components at common node before principal or vector
sum calculation except for the von Mises equivalent strain (EQV),
see below.

## Notes

Selects the method of combining components for certain derived
nodal results when two or more elements connect to a common node.
The methods apply to the calculations of derived nodal principal
stresses, principal strains, and vector sums for selects, sorts, and
output [**NSEL**, **NSORT**, **PRNSOL**, **PLNSOL**, etc.].

This command also defines the effective Poisson's ratio (`EFFNU`

) used for equivalent strain calculations. If
you use `EFFNU`

, the default effective Poisson's
ratios shown below will be overridden for all elements by the `EFFNU`

value. To return to the default settings, issue
the **RESET** command. The default value for `EFFNU`

is:

Poisson's ratio as defined on the **MP** commands for EPEL and EPTH

0.5 for EPPL and EPCR

0.5 if the referenced material is hyperelastic

0.0 for line elements (includes beam, link, and pipe
elements, as well as discrete elements), cyclic symmetry analysis, mode
superposition analyses (with `MSUPkey`

=
YES on the **MXPAND** command), and load case operations
(**LCOPER**).

For the von Mises equivalent strain (EQV), it is always computed
using the average of the equivalent strains from the elements at a
common node irrespective of the value of the averaging `KEY`

. If `EFFNU`

is input,
though, the calculation will be performed according to the `KEY`

setting.

For a random vibration (PSD) analysis, issuing either **AVPRIN**,0 or **AVPRIN**,1 calculates the
principal stresses using the appropriate averaging method. They are
then used to determine SEQV. The output will have non-zero values
for the principal stresses.

If **AVPRIN** is not issued, the Segalman-Fulcher method is used to calculate SEQV. This method does not calculate principal
stresses, but directly calculates SEQV from the component stresses;
therefore, the output will have zero values for the principal stresses.
Beam and pipe elements are excluded

This command is also valid in POST26, where applicable.

See Combined Stresses and Strains in the *Mechanical APDL Theory Reference* for more information.