XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX''"> Basic Concepts and Definitions
Analysis results values are highly specific to the type of analysis, what options you have set, and the analysis software used. Hence, the results that you receive and the form that they are in depends a great deal on the analysis and not on Patran. At the same time, the Patran results interface will input results in a common format for use in its postprocessing menu forms.
It is important to note that analysis results are not read in during postprocessing (e.g., using the Results Display form). Instead, they are read in or referenced following the Analysis, using the Analysis menu form. In the event that you have entered a postprocessing menu form and see no result cases available for display, the chances are good that either the analysis itself did not complete, or Patran cannot locate the appropriate results file.
Types of Analysis Results
Most analysis results take one of three forms: scalar, vector, or tensor values.
• Scalar results are comprised of a single variable, such as the temperature at a point. A scalar result also can be (and often is) a component value of a multi-dimensional result, such as the X-component of the displacement vector or the magnitude of the stress at a point. Scalar quantities can be displayed by techniques such as color-coded fringe plots, where the color corresponds to the result value, or used as variables in an X-versus-Y graph of result values.
Figure 10‑1 Color fringe plot of scalar result values
• Vector results are three-dimensional quantities linked to the components of a coordinate system--in other words, results which are spatial in nature. Vector results may include quantities, such as displacement, stress, or electromagnetic field values. Spatial vector results such as displacements, can be shown using a deformed shape plot that exaggerates the displacements applied to the model, or a marker plot that displays symbols corresponding to the vector quantity at each of several points in the model.
Figure 10‑2 Deformed shape plot of vector quantities
• Tensor results can be viewed as a "vector of vectors," and commonly occur when there is an interdependence between vector quantities. A good example of a tensor quantity in a structural analysis is shear stress, for example, with components related to individual or pairwise combinations of each of the principal coordinate directions. Tensor fields consist of nine values at each discrete point within the model, and can be displayed as marker plots. Actual tensor values can also be displayed.
Result Cases
Result values are grouped into what are called result cases, containing all of the results data for one step of the analysis. These steps could consist of individual static load and boundary condition cases, for example, or may represent results at individual time or frequency points within these solution domains. No matter what the source of the analysis results, Patran generally displays one or more result cases within its results menus.
Even when there is only a single result case available, one result case must be selected before results display can be performed. Once a result case is selected, a list of which results are available for this case is shown in another menu field.
Depending upon which type of results display is being used in Patran, an appropriate result type must be selected. For scalar displays of vector quantities such as stress or displacement, an additional field will allow you to select the component of this result, for example, the equivalent stress or the X component of a displacement.
Some of the more advanced display options in Patran enable you to derive further results from these analysis results, such as a combination of two result sets. This is performed using an optional menu from these forms. First, however, it is important to understand how to create basic results images from the data you get directly from your analysis program.
Graphical Displays of Result
You can visualize your numerical results using three basic types of displays.
• Fringe plots. These plots are similar to a topographic map, in that they use color to show scalar result values on the surfaces of a model. Each color represents a particular range of values, and the boundaries between colored regions can be seen as lines of the constant result value at each range boundary. In general, "hotter" colors (such as red) represent higher result values while "cooler" colors (such as blue) represent lower values, although this can be changed by modifying your spectrum, discussed later in this chapter.
• Deformed shape plots. For problems where there is deformation in the model, a deformed shape plot shows the model in its deformed position. By default, a scaling factor is used to exaggerate these displacements for better visibility, and this factor can be either a multiplier of actual displacements or a value that can scale the maximum displacement to a percentage of the screen size.
• Animation of fringe and/or deformed shape. When you select the Animate option, an animated display is produced that varies the fringe plot from zero (all white) to its full color values, and varies the deformed shape from rest to its fully deformed position.
