The units of a user defined result are defined by the following Detail view settings:
Input Unit System: A read-only field that displays the active Mechanical application unit system. To evaluate an expression, a user defined result's units must be converted to the Input Unit System. As a result, the expression is most easily verified when the intervening data is viewed in the Input Unit System.
Output Unit: The physical dimension assigned to a user defined result. It determines which factors are used to convert the result from its Input Unit System to the current unit system selection. A large list of unit types is available. Because you can assign such a wide variety of unit types to a result, Ansys recommends that you choose carefully and be consistent.
Units are defined in a two step process.
Before you evaluate an expression, the units are converted to the Input Unit System.
Once evaluated, values are converted from the input system to the active Mechanical application unit system using the appropriate factor.
For example, given the following user defined result expressions with MKS (m, kg, N, ºC, s, V, A) units:
FORCE_MKS=FSUM
STRESS_MKS=SEQV
DISP_MKS=USUM
If you change the unit system to CGS (cm, g, dyne, ºC, s, V, A) and create a new user defined result with
Expression=FSUM+SEQV+USUM while assigning as the Output Unit, you will
produce the following user-defined results:
| Custom Identifier | Expression | Input Unit System | Output Units |
| FORCE_MKS | FSUM | Metric (m, kg, N, s, V, A) | Force |
| STRESS_MKS | SEQV | Metric (m, kg, N, s, V, A) | Stress |
| DISPL_MKS | USUM | Metric (m, kg, N, s, V, A) | Displacement |
| VOLUME_CGS | FSUM+SEQV+USUM | Metric (cm, g, dyne, s, V, A) | Volume |
The expression VOLUME_CGS is easy to verify for its Input Unit System, CGS. If FSUM=3 dyne, SEQV=17 dyne/cm² and USUM=2 cm, (as seen in when CGS is selected in the Mechanical application), VOLUME_CGS produces the value 22 cm³. Any subsequent changes to the unit system in the Mechanical application cause each of the user defined results to convert based on their required factors. In this manner, VOLUME_CGS will use a factor of 1000 to convert from Metric CGS to Metric mm, because it represents a Volume. FORCE_MKS, STRESS_MKS and DISPL_MKS will convert differently, based on the selected Output Units.