Because PowerGraphics plots or listings are given for the exterior surface of the model, expect to see differences in the results compared to those given when using the Full Model method.
The averaging calculations for PowerGraphics include results for only the model surface. The averaging calculations, plots, and listings for the Full Model method include results for the entire model (interior and exterior surfaces). The PowerGraphics and Full Model methods therefore display results values differently for nodal results.
The EPLOT, APLOT, VPLOT, LPLOT, PLDISP, PLNSOL, and PRNSOL commands behave differently for PowerGraphics than for Full Model.
The subgrid approach used by PowerGraphics enables you to control the amount of displayed element curvature. You can plot varying degrees of curvature in your model by specifying the number of facets to be used for element display. Facets are piecewise linear approximations of the actual curve represented by the element face or edge. Specify the number of facets per element edge via the /EFACET command.
The more facets you specify, the smoother the representation of the element surface for PowerGraphics plots.
The subgrid approach affects both the display of geometric curvature and the display and printout of results quantities (displacements, stresses, etc.). When using PowerGraphics in POST1 for derived quantities on solid elements, however, the maximum value on the plot and the maximum value in the printout may not agree. PowerGraphics displays do not average at geometric discontinuities. The printouts in PowerGraphics will, however, provide averaging information at geometric discontinuities if the models do not contain shell elements. Carefully inspect the data you obtain at geometric discontinuities.
List displacements, stresses, and strains at all node locations (both corner and midside nodes), via the PRNSOL command.
For shell elements, you can list results and plot them at the top/bottom and middle layer locations. Likewise, these nodal values can be contoured for display purposes. The number of facets per element edge that you specify determines contour resolutions.
Results values for shell elements are displayed simultaneously for the top and bottom layers.
When viewing nodal results via PowerGraphics (PRNSOL, or PLNSOL), you can average results in various ways. To specify how results are averaged, issue the AVRES command. (The command has no effect on the degree-of-freedom (DOF) solution values (UX, UY, TEMP, etc.). You can average results at all boundaries (default), or at all boundaries except where real constant and/or material discontinuities exist. Results are not averaged at geometric discontinuities.
In Full Graphics mode, it is possible to deselect an individual node, select all elements (including the element that contains that node), and then perform postprocessing calculations on those elements and have that unselected node not be considered in those calculations. However, if PowerGraphics is active postprocessing always displays based on selected elements.
The minimum and maximum results values reported for your PowerGraphics plot are based on the surface data. For stresses and strains, the values are usually acceptable. Some thermal results, however, may have internal minimum or maximum values, and erroneous values may be reported. In such cases, switch to Full Model graphics.
Plotting and printing element results is similar to the Full Model graphics method. Issue the PLESOL or PRESOL command.
The program unaverages nodal results and sorts them by element number. Averaging results does not affect element results plots. Results are for all nodal locations on the model surface. If you issued the /EFACET,1 command, the results for the midside nodes are not listed.
PowerGraphics does not support safety factor calculations.
In unusual cases, your model may contain element types having different results data sets. If so, unselect those element types which do not have the data set you are reviewing. Doing so prevents zero values from being averaged with valid results. For example, if your model contains FLUID30 (Acoustic Fluid) and SOLID185 (Structural Solid) elements, unselect all SOLID185 elements before viewing a pressure gradient.