This section describes several important concepts and functions that are related to the Patran Element Properties application.

Element types help to define the physical characteristics of the model. The table below lists the supported element types for MSC Nastran structural analyses (the options for element types are analysis code-specific and analysis type-specific). You will notice in looking at the table that a 2D plane element can be a shell, bending panel, 2D-solid, membrane, or shear panel. All of these element types can be constructed with the same element topology choices (quad or tria shapes, with varying node configurations), but they take on the attributes of the element type when the element property is applied .

The attributes of the different element types are an important topic in engineering, and it is beyond the scope of this guide to describe the attributes of a shell versus a bending panel, and so on. They are differentiated by characteristics such as how the structure is likely to behave given particular load conditions; for example, whether stress and strain on the structure will remain within a plane, and what the degrees of freedom are for movement of the structure.

Modeling structures composed of beams can be more complicated than modeling shell, plate, or solid structures. First, it is necessary to define bending, extensional, and torsional stiffness that may be complex functions of the beam cross sectional dimensions. Then it is necessary to define the orientation of this cross section in space. Finally, if the centroid of the cross section is offset from the two finite element nodes defining the beam element, these offsets must be explicitly defined. Fortunately, Patran provides a number of tools to simplify these aspects of modeling.

To make the task of modeling beam elements easier, the MSC Nastran analysis code provides a special beam library that adds extensions to the basic Patran element property modeling forms. The Beam Library forms are a much more convenient way of defining properties for standard beam cross sections. They include special functions for I-beams, Tubings, tube beams, and more.

The Element Properties form allows you to choose many combinations of Dimension, Type, Options, and Topology. The table below lists many of the possible combinations of options for two-dimensional elements in MSC Nastran.

Particular combinations of element property options are given special names. A commonly used element in MSC Nastran is the Standard Homogeneous Plate. This element results from choosing a combination of 2D, Shell, standard, homogeneous, and quad4 topology on the Element Properties form.

To assign the element property sets you have defined to the analysis model, you must specify an Application Region on the Element Properties form. You can specify the Application Region as a collection of one or more FEM or geometric entities. You can either type the entity names, or select them in the modeling viewport.

Properties associated with geometry will be re-applied to the model after remeshing. Properties associated with FEM entities have to be recreated if the model is remeshed.

All the Element Property sets you create are associated with an analysis code and type, selected using the Preferences/Analysis menu or the New Model Database form. If you change the analysis code or type preference, the existing element property sets are modified to use the closest matching element type in the new preference environment. All applicable property data is automatically transferred.

Changing back to the original analysis code will not necessarily restore the element property definitions to their original state if there is no direct mapping. To run the same problem on different codes while maintaining the original state of the element property definitions, copy the database, change the analysis preference, and then make the appropriate changes to element properties, materials, loads, etc.

A property is any information required to define FEM element properties, as required by an analysis code. These include thickness, spring constants, areas, degrees-of-freedom, offsets, directions, masses, material names, etc. Each property is of a specific type. There are nine different property types: Integer, Real Scalar, Real Scalar List, Vector, Material Name, Character String, Node, Coordinate Frame, and Nodal Field Name. Every Property is classified as one of these types.

Each element property set has an associated name and number. You provide the set names, which may be from one to 31 characters. The numbers are assigned in sequence by Patran. The only place you will see numbers displayed is in the Show/Marker Plot option.

A Field is a scalar or vector quantity that is a function of up to three independent variables. A field name is prefixed by f: and can be defined by a table or PCL expression. An example would be the thickness distribution of a shell. Within the Element Properties application, fields usually define property distributions that vary spatially.

The Element Properties application Show action allows you to select marker plots, scalar plots, and tabular plots for viewing the element property sets that have been assigned to regions of your model.

Select this action to view markers, graphic symbols that provide visual feedback about the location, magnitude, and direction of displayed element properties. To remove them from the screen, turn off the General Marker display in the Display/Functional Assignments menu, or click on the Broom icon to clear the display.

Select this action to view specified element properties in your model using a fringe plot. To remove the plot from the screen, select the Display/Entity Types menu and change the Render Style to Wireframe or click on the Broom icon to clear the display. For display purposes, data is treated as results, with full user control over the spectrum, method, shading, etc. Data display is scalar, of course, but the data can be any nonvector element property.

Another way to view element properties in your model is to display a table which lists all elements with the selected property in the current viewport or all viewports in sequence along with the associated Set Name(s), Property Type, and Value.